xm 



PHYLUM CHORDATA 



189 



Each hemisphere is continued in 

 tube, the olfactory peduncle (olf. 

 compressed olfactory bulb (olf. I.). 



The optic nerves (Nv.2) form a 

 chiasma. The pineal body (pn.b.) 

 is a small rounded vesicle borne 

 on a hollow stalk (pn. s.) which 

 runs just outside the posterior 

 wall of the tent-like choroid 

 plexus. The pituitary body (pty.) 

 consists of intra- and extra-cranial 

 portions, the former lodged in the 

 sella turcica, the latter in the pit 

 already noticed on the ventral or 

 external face of the skull-floor 

 (Fig. 861, pt.). In advanced em- 

 bryos the two are united by a 

 delicate strand of tissue. 



Urinogenital Organs. The 

 kidneys (Fig. 863, Ted.) are lobed, 

 deep-red bodies, like those of the 

 Dog-fish, but shorter and stouter. 

 In the male they are much longer 

 than in the female ; the anterior 

 portion is massive, and consists 

 mainly of a mass of true renal 

 tubules ; it is indistinctly divided 

 into segments : the posterior 

 portion is narrower and also 

 indistinctly segmented ; from 

 both parts arise a number of 

 ducts (mesonephric ducts) the 

 majority of which open into the 

 vas deferens, while the last six 

 open into the urinogenital sinus. 

 In the female the ducts all open 

 into a rounded median urinary 

 bladder or urinary sinus, situated 

 between the two oviducal aper- 

 tures. The female reproductive 

 organs are also .constructed on 

 the Elasmobranch pattern, and 

 are chiefly noticeable for the 

 immense size of the shell-glands 

 and of the uteri. But the male 

 organs present certain quite 

 unique characters. The testes 



front into a slender thin- walled 

 p.), bearing at its extremity a 



FIG. 863. Callorhynchus antarcticus. 

 A, male urinogenital organs of left side- 

 ventral aspect ; B, anterior part of vesicula 

 seminalis in section, cl. cloaca ; epid. epi- 

 didymis ; kd. kidney ; mill. d. Miillerian 

 duct ; sph. spermatophores ; ts. testis ; 

 u. g. s. opening of urinogenital sinus ; 

 v. df. vas deferens ; vs. sem. vesicula 

 seminalis. (A after Redeke.) 



