XIII 



PHYLUM CHORDATA 



233 



coelome. An ovary of this kind reminds us of the state of things 

 in Arthropods, in which also the ovary is a hollow organ dis- 

 charging its products into its internal cavity, whence they pass 

 directly into the continuous oviduct. It was pointed out that the 

 lumen of the ovary in this case was to be looked upon as a shut-off 

 portion of the coelome : this is certainly the case in Lepidosteus 

 and the Teleostei. In 

 the embryo a longi- 

 tudinal fold grows 

 from the ventral edge 

 of the then solid ovary, 



<z 



B 



and .turns upwards 



along s the lateral face 



of the^organ : it is met 



by a ^descending fold 



of peritoneum from 



the dorsal wall of the 



abdomen, and by the 



union of the two folds 



a cavity is enclosed, 



which is the lumen of 



the ovary. The ovi- 



duct is developed as a 



backward continuation 



of these folds of peri- 



toneum, and appears 



to be quite uncon- 



nected with the em- 



bryonic renal system, 



and therefore not to 



be homologous with 



the oviducts of Elas- 



mobranchs and Holo- 



cephali, which, as we 



have seen, are Miil- 



lerian ducts. In the 



Salmonidae and the 



Eels oviducts are 



absent, and the ova 



are discharged by 



genital pores, which are probably to be looked upon as degenerate 



oviducts. True abdominal pores are present in Ganoids and in some 



Physostomi. Most Teleostomi are dioecious, but Serranus, one of 



the Perch family, is hermaphrodite and self-impregnating ; Chryso- 



phrys is hermaphrodite and successively male and female ; and there 



are many well-known species, such as the Cod and the Herring, which 



exhibit the hermaphrodite condition as an occasional variation, 



FIG. 9U8. Female organs of Lepidosteus (A) and Amia 

 (B). a, degenerate anterior portion of kidney ; bl. bladder ; 

 kd. kidney ; ovd. oviduct ; ovd.' aperture of oviduct into 

 bladder ; ovd." peritoneal aperture ; ovy. ovary ; p. peri- 

 toneum ; u.g. ap. urinogenital aperture; ur. ureter. (-4, 

 after Balfour and Parker ; B, after Huxley.) 



