1919-] T. SouTHWEivi. & B. Prashad : Studies of Indian Fishes. 235 



persisted as such, and not resulted from a retransformation of the 

 placental cord into a yolk-stalk. Further, the condition of 

 aplacental viviparity amongst the Batoids is to be derived directly 

 from that in the oviparous Elasmobranchs and not that in the 

 viviparous forms with a placental development. In fact, there 

 are two distinct lines of development from the oviparous con- 

 dition, (i) Viviparity with the development of a placenta, (ii) apla- 

 cental viviparity. The correct name, therefore, for the structure 

 in these aplacental viviparous Batoids is the yolk-stalk or the 

 stalk of the volk-sac. 



The Appendicui^a of some of the Indian Carcharidae. 



We have thought it necessary to deal with these structures as a 

 whole in the various species that we have had a chance to examine. 



Johannes Miiller ' in his admirable resume of all that was 

 known up to 1840 regarding the uterine structures, etc. in the Sela- 

 chians does not mention any such processes in the text, or show 

 any of them in the beautiful figures of the various species at the 

 end of his paper. The species dealt with by him are Mustelus 

 laevis , Mustelus vulgaris and Carcharias (Prionodon) sp. Alcock * is 

 the only author, so far as we know, who has given an account of 

 these structures, and it is to him that we owe the very appro- 

 priate name of appendicula. He described these structures for 

 Zygaena hlochii as follows: — "The placental cords, which were 

 much more delicate, were uniformly covered, except at the 

 extreme foetal end, with flattened, leaf-like, bilobed or trilobed 

 appendicula, from one-eighth to one-quarter of an inch in length, 

 each lobe being one- eighth of an inch broad." For the embryos of 

 the other two species {viz. Carcharias melanopterus and Carcharias 

 dussumieri), also described in the same paper, no appendicula are 

 mentioned as being present on the placental cord. There are 

 no other references to these structures in the literature consulted. 



We have examined the embryos of the following species : 

 Scoliodon sorrakowah, S. palassorah, S. walheehmi and two other 

 species of Scoliodon, the specific identification of which we are 

 not certain, and of a Cestracion sp.^ The results of our study of 

 these structures show that there are at least four different types 

 of appendicula in the species studied. 



Type (i). — In a single specimen of Scoliodon sp. collected from 

 the coast of Ceylon the placental cord is very long, measuring 

 about 19 cm. The placenta is of the usual arborescent type and 

 is attached to a portion of the uterine wall which was preserved 

 along with the embryo. The placental cord is fairly thick, 5 mm. 

 in diameter exclusive of the appendicula ; its wall is thrown into 



1 Abhaud. Ak. Wiss. Berlin, 1840, p. 188. 



2 Journ. As. Soc Bengal, LXIX (ii), p. 51 (1890). 



5 According to Garman, loc. cit., p. 155, Cestracion is the correct generic 

 name for what has until recently been known as Zygaena. 



