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STUDIES IN AUSTRALIAN SHARKS, No. 2. 

 By Edgar R. Waite, F.L.S. Zoologist. 



Galeus antarcticus, Gilnther. 



(Fig. 19). 



It was known to Aristotle, some 350 years B.C., that of two 

 common " Hounds " of the Mediterranean, the embryos of one 

 were developed by the medium of a placenta produced in the 

 uterus, and that the embryos of the other were developed without 

 such placenta. The condition in the former species, Mustehis 

 Icevis, is thus described by Balfour^: — "The vascular surface of 

 the yolk-sack becomes raised into a number of folds, which fit 

 into corresponding depressions in the vascular walls of the uterus. 

 The yolk-sack becomes in this way firmly attached to the walls 

 of the uterus, and the two together constitute a kind of placenta." 



In 1 882, the late Prof. T. J. Parker made the interesting discovery 

 that the emhvyos oi Galeus antarcticus do not lie freely in the uterine 

 cavity, but are each confined in a separate compartment. I quote 

 the following passage": — "I was considerably surprised to find, on 

 dissecting a gravid female of M. antarcticus, that the relations 

 between the mother and the fcetus were nothing like so simple as 

 I had expected, but that, just as the Mustelus levis [Icevis] furnishes 

 a sort of foreshadowing of the true placenta of mammals, so M. 

 antarcticus is provided with membranes which, although formed 

 from the maternal and not from the foetal tissues, foreshadow in 

 a remarkable manner the chorion and the amnion." 



It was perhaps a careless reading of this passage which led me, 

 in a recent work, to write as follows": — "Parker has described 

 how, in this species, the embryo is attached to the uterus with a 

 placenta." This matter is again brought under my notice from 

 the circumstance that on June 10th last, the Trustees received 

 material which fell to my lot to examine. 



On the previous day a man fishing in Maroubra Bay caught a 

 Shark, and finding that it contained young, sent them, together 

 with some viscera, to the Museum. I first picked out a young 

 one for determination, and identified it as Galeus antarcticus. 

 Turning to the other contents of the bottle, I saw that it included 

 portions of the uteri, considerably torn. Each uterus is divided 



1 Balfour — Comp. Embryology, ii., 1881, p. 54. 



2 Parker— Trans. N.Z. Inst., xv., 1883, p. 219. 



3 Waite— Aust. Mus. Mem., iv.. Fishes, 1899, p. 33. 



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