1890.] A. Alcock — On the Gestation of Elasmobranch Fishes. 53 



is no gland- like body in connexion with the artery. The red blood-cells 

 of the fcetns are y^- -$ of an inch in the major, and -^Vo of an inch 

 in the transverse diameter. 



The length of the foetuses was about fifteen inches. 



The nature of the appendicula is difficult to understand, seeing that 

 the foetus is connected with the mother by a large and well-developed 

 placenta ; but their richly cellular investment is evidence of some active 

 function, either in the elaboration or purification of the blood proceeding 

 to the foetus. If the channels of the cord are regarded as lymphatics, 

 the appendicula might be looked upon as forming a diffused and pri- 

 mitive lymphatic gland-system, their thick investment of lymphoid cells 

 being analogous to the medulla of a mammalian lymphatic gland. 



c. Carcharias dussumieri. A female, seven feet and a half long, 

 was hooked at sea, off the west coast of Middle Andaman Island, on the 

 13th of April, 1889. 



Immediately after death, lively movements commenced in the ab- 

 domen, which was much distended ; and the abdominal cavity, on beino- 

 opened, was found almost completely filled by the dilated, congested, 

 spongy- walled uteri, as in the case of Carcharias melanopterns and Zygcena 

 blochii. Bach uterus contained five living foetuses, each two feet lone- 

 lying head forwards in separate compartments, each with its own 

 placenta, exactly in the manner already described. The placental cords 

 had the usual appearance. 



The young ones when removed to a tub of sea- water swam about 

 vigorously for nearly an hour, but died eventually from hemorrhage 

 due to rupture of the placental cord. 



The structure of the placenta, and the distribution of the vessels 

 of the cord, were exactly similar to those of 0. melanopterus ; but no 

 gland-like organ was found on the artery. 



Unfortunately, the selected specimens, though placed in strong 

 alcohol, putrified. 



The specimens of Carcharias melanopterus and Zygcena blochii 

 though packed in salt, became so rotten that they fell to pieces. 



§ 2. Observations on the Gestation of Trygon bleekeri, and on the 

 Uterus of Myliobatis nieuhofii. 



a. Tbtgow bleekeri. A female, with a disk of very larcre dimen- 

 sions, was taken in the seine, by Mr. W. H. W. Searle, in False Point 

 Harbour (Orissa coast), on the 15th December, 1888. 



The distal end of the right oviduct was enormously dilated, and 

 contained in its cavity a fully-developed male foetus with a disk ll- 2 - 

 inches long and 101 inches broad. 



