Part 27

Color.--As described in Mustela erminea richardsonii except that least width of color of underparts averaging, in five females, 42 (35-53) per cent of greatest width of color of upper parts. Black tip of tail in same specimens averaging 36 (30-40) mm. which is 49 (48-53) per cent of length of tail-vertebrae.

Skull.--Male (based on 8 adults from Windham): See measurements and plates, 2-4. As described in Mustela erminea richardsonii except that: Weight, 1.8 (1.5-2.6) grams; basilar length, 37.5 (36.5-38.9); length of tooth-rows more or less than (about same as) length of tympanic bulla.

Female (based on 5 adults, from localities listed in the table of cranial measurements): See measurements and plates 9-11. As described in Mustela erminea richardsonii except that: Weight, 0.96 (0.7-1.1) grams; basilar length, 32.7 (31.9-33.2); breadth of rostrum more or less than (about equal to) 30 per cent of basilar length.

From richardsonii, alascensis differs in that the skull of the male averages smaller in every measurement taken and is 28 per cent lighter. Relative to the basilar length, the orbitonasal length is more and the braincase is shallower as measured at the anterior end of the basioccipital. The four adult females seen of alascensis are more variable than those of richardsonii and average smaller in some measurements and larger in others but give no proof of any consistent difference.

From haidarum, alascensis differs in that the rostrum and entire preorbital part of the skull is actually as well as relatively much smaller in both sexes. In males of alascensis the length of the skull, and other cranial measurements of length, is more. In males, the mastoid breadth and zygomatic breadth are about the same as in haidarum, as also is the weight. M1 is larger but m1 and P4 are smaller. In females the anteroposterior extent of the inner moiety of M1 and length of tympanic bulla are about the same in the two subspecies but all other cranial and dental measurements in alascensis are less. It is 29 per cent lighter. The difference in the preorbital region is of about the same degree as in the males.

Comparisons of the skull with those of arctica, salva, initis, celenda, and seclusa are made in the accounts of those subspecies.

Remarks.--The relatively few specimens known of this race seem always to have been referred to in the literature by the name alascensis and the nomenclatural history is therefore simple. The original materials were obtained by the collector Clark P. Streator and the additional series of skeletons, one with skin, from Windham were procured by Stanton Price, a resident there.

The subspecies is well differentiated from both arctica and richardsonii. Although actual intergrades are lacking between alascensis and the two races just mentioned I have no doubt that intergradation occurs with richardsonii and think it probably does also with arctica.

The assignment of the three females from Mitkof Island, Zarembo Island, and Loring on Revillagigedo Island, is tentative because each is so young as not to show diagnostic cranial characters. The two other specimens from Revillagigedo Island (Carroll Inlet), labeled as males, are in white winter pelage. Only one, no. 136358, a subadult, is accompanied by a skull. The small size of each specimen, and its cranial characters which are intermediate between those of males and females of alascensis of the adjacent mainland, indicate the existence of a distinct race of weasel on Revillagigedo Island. On the chance that the one specimen with a skull is a dwarf, or is wrongly sexed as seems improbable, the population is tentatively referred to alascensis.

Specimens examined.--Total number, 24, arranged by localities from north to south. Unless otherwise indicated, specimens are in the Museum of Vertebrate Zoölogy, University of California.

=Alaska.= Juneau, 5; Taku River, 1; Windham, 9; Mitkof Island, 1; St. John Harbor, Zarembo Island, 1; Wrangel, 1; Helm Bay, Cleveland Peninsula, 1; Cleveland Peninsula, 2; Revillagigedo Island, Carroll Inlet, 2; Loring, 1.

=Mustela erminea salva= Hall

Ermine

Plates 2, 3, 4, 9, 10 and 11

Mustela erminea salva Hall, Proc. Biol. Soc. Washington, 57:35, June 28, 1944; Hall, Journ. Mamm., 26:180, July 19, 1945.

Type.--Male, adult, skull only; no. 74641, Mus. Vert. Zoöl.; Mole Harbor, Admiralty Island, Alaska, December 27, 1936; obtained by A. Hasselborg.

The skull (plates 2-4) shows malformation of the frontal sinuses owing to parasites and lacks osseous tissue where the parasitic infestation was localized. The skull is unbroken. The teeth all are present and entire.

Range.--Admiralty Island, Alaska. See figures 25, 26 on pages 95, 134.

Characters for ready recognition (known only from skulls).--Differs from males of M. e. alascensis in overall depth of braincase which is more than 89 per cent of orbitonasal length; from M. e. initis, in males, in that orbitonasal length and mastoid breadth total less than 35 mm., weight of skull and lower jaws less than 2.1 grams; from M. e. celenda, in males, in that breadth of rostrum measured across lacrimal processes less than a third of basilar length.

Description.--Size.--Male: An adult from Gambier Bay measures: Total length, 320; length of tail, 95; length of hind foot, 45 (41 in dry skin).

Female: A subadult from Hawk Inlet, measures: Total length, 250; length of tail, 70; length of hind foot, 33.

Color.--As described in Mustela erminea richardsonii except that least width of color of underparts in four individuals 40 (38-43) per cent of greatest width of color of upper parts. Black tip of tail, in two individuals for which external measurements are given, amounting to 50 and 40 mm. respectively which is 53 and 57 per cent of length of tail-vertebrae.

Skull.--Male (type and 4 adult topotypes): See measurements and plates 2-4. As described in Mustela erminea richardsonii except that: Weight, 1.7 (1.5-1.9) grams; basilar length, 37.8 (36.4-39.5, extremes are in subadults); length of tooth-rows more or less (usually more) than length of tympanic bulla; interorbital breadth rarely more than distance between glenoid fossa and posterior border of external auditory meatus.

Female (2 ad. and 1 ad.-sad. topotypes): See measurements, and plates 9-11. As described in Mustela erminea richardsonii except that: Weight, 0.9 (0.8-1.0) grams; basilar length, 33.0 (32.0-33.6); length of tooth rows approximately same as length of tympanic bulla; breadth of rostrum approximately 30 per cent of basilar length.

From alascensis, salva differs in that males have the preorbital region slightly wider in relation to the length of the tympanic bulla; also the braincase is smaller, actually as well as in comparison with the preorbital part of the skull. The tympanic bullae do not project so far below the squamosals and the braincase itself is shallower, in adults averaging only 11.5 mm. as against 12.5 mm. The overall depth of the braincase, including the tympanic bullae, when divided into the orbitonasal length gives an average of 93 (90-97) per cent whereas in alascensis the figure is only 85 (78-88) per cent. On this basis alone, everyone of the adult skulls of the two races can be distinguished. The females and subadult males show the same tendency to reduction in depth of braincase but not every individual among them can be surely distinguished. By weight the skull of salva of corresponding sex is only about 6 per cent smaller. Comparisons with initis and celenda are made in the accounts of those subspecies.

Remarks.--Most of the specimens seen were collected by Allen E. Hasselborg, resident on Admiralty Island. On the basis of skulls--few skins, and measurements taken in the flesh, are available--salva more closely resembles alascensis than does any other subspecies so far known from southeastern Alaska. The race on Admiralty Island is only slightly differentiated from alascensis of the adjacent mainland.

Specimens examined.--Total number, 26, all from Admiralty Island, Alaska, arranged in general by localities from north to south, and unless otherwise indicated in the Museum of Vertebrate Zoölogy, University of California.

=Alaska.= Admiralty Island: Hawk Inlet, 2; Seymour Canal, 4; Mole Harbor, 18 (skulls only); Gambier Bay, 1; no locality more definite than Admiralty Island, 4 (1 in U. S. Nat. Mus.).