490 CHORDATA. 
secretes the shell. They have no distinction into Fallopian 
tube, uterus and vagina, and they open separately into the 
urogenital sinus. 
Fig. 334. VENTRAL VIEW OF PECTORAL GIRDLE AND 
Fore-LiMB OF ORNITHORHYNCHUS. (Ad zat.) 
Episternum, 
Clavicles. 
| 
| Scapula, 
ig 
; 
4 Humerus. _ 
Radius. 
| 
| 
‘Ulna. 
3. CLoaca.—The urogenital canal and the alimentary 
canal have a common passage called the cloaca which opens 
by a single aperture to the exterior, the cloacal aperture 
(hence Afonotremata). 
Fig. 335.—PELVIS OF ORNITHORHYNCHUS x 4. (Ad nat.) 
Sacrum. Tlium. 
Epipubic. ~-= 
Pubis.—@ . / : Acetabulum. 
Obturator Fora- 2 i i 
men. 
Ischium.” 
g : 1 
A Epipubis. B Ischium. 
A, Ventral view. B, Lateral view. 
4. SKELETON. — Shoulder-girdle has complete precora- 
coids, coracoids and episternum. The scapula is bent 
forward and the spine is at the anterior border, not down 
the middle. 
