Part 6

(c) The ureters which run along the outside of the kidneys and unite posteriorly to form a single duct opening into the cloaca.

In the female Platana note:--

(a) The ovaries, a pair of irregularly-lobed organs usually consisting of a mass of rounded black and white bodies, the ova. The ovaries are attached to the dorsal wall of the body cavity by a fold of the peritoneum.

(b) The corpora adiposa lying in front of the kidneys.

(c) The long convoluted oviducts opening into the body cavity in front and into the cloaca behind.

The ureters open separately into the cloaca in the female.

Make a drawing of the urinogenital system.

Fifth Day.

=Skeletal System= (continued).

A. The Pectoral and Pelvic Girdles and Limbs.

1. Detach a fore-limb with the remaining parts of the pectoral girdle. Make a preparation showing these various parts:--

Supra-scapula, scapula, remainders of the clavicle and the coracoid, humerus, radio-ulna, carpal bones, and digits. Draw these parts.

2. Detach the pelvic girdle from the transverse processes of the 9th vertebra. Remove it with the hind-limbs from the body. Detach the femur from one side of the pelvic girdle, and make a sketch showing the following parts of the pelvic girdle:--Acetabulum, ilium, ischium, and pubis.

Make a preparation and a sketch showing the femur, tibia-fibula, astragalus, calcaneum and the other bones of the tarsal region, five metatarsals, and digits. Number the digits from the inner side.

B. The Vertebral Column.

1. Remove the skin and muscles from the dorsal surface of the back to show the nine vertebræ and the urostyle. Make a drawing showing the vertebræ with their transverse processes, and the urostyle attached to the posterior end of the 9th vertebra.

The 2nd, 3rd and 4th vertebræ bear long transverse processes curved backwards, those of the 3rd and 4th being tipped with small cartilaginous ribs. The transverse processes of the 5th, 6th, 7th and 8th vertebræ are slender and project forwards and outwards. The 9th vertebra has long flat wing-like processes attached to which are the ilia of the pelvic girdle. The urostyle is fused to the 9th vertebra.

Note the intervertebral foramina for the exit of the nerves from the spinal cord, and the intervertebral discs.

2. Remove, examine, and draw the 1st or atlas vertebra, note its ring-like form, absence of transverse processes, the concave facets by which it articulates with the two occipital condyles of the skull.

3. Remove, examine, and draw the 3rd vertebra and note the opisthocœlous centrum, neural arch and neural spine, anterior and posterior zygapophyses, the transverse processes, and the cartilaginous ribs.

4. Remove and examine the 8th vertebra and note that the centrum is opisthocœlous. Make a drawing of a section showing the centrum.

5. Remove and examine the 9th vertebra or sacrum, and note that the centrum is slightly convex on the anterior surface. The urostyle is fused to the posterior surface of the 9th vertebra. Note also the long flat wing-like transverse processes.

Sixth Day.

=Skeletal System= (continued).

C. The Skull.

1. Remove the skin and other tissues from the top of the skull and observe the large fronto-parietals, nasals, supra-ethmoid, premaxillæ, maxillæ, squamosals, exoccipitals, and pro-otics. The quadrato-jugals are very inconspicuous. The extrastapedial plate of cartilage is well marked and the bony columella may be seen lying underneath it. The sides of the skull are ossified and may represent the orbitosphenoids and alisphenoids of higher types. The supra-occipital consists of a piece of cartilage.

Make a drawing of the dorsal side of the skull.

2. Remove the skin from the roof of the mouth and note the parasphenoid and single vomer, pterygoids, which are large and send leaf-like processes towards the middle line covering the Eustachian passages, squamosals, quadrates, basi-occipital, ex-occipitals, premaxillæ, and maxillæ. The orbitosphenoid and alisphenoid are well marked. There are no palatines present.