Utero-gestation in Try-on Blcekcri. 425 



Elasmobrancli fishes, remain as direct cliannels between the 

 pliarynx and the external medium. 



There is also noticed a small external yolk-sac about as 

 big as a raisin, with a thread-like stalk which perforates the 

 body-wall, and, ex|)anding', is attached to the anterior end of 

 the spiral ^t;ut on the ventral aspect. 



The yolk-sac is empty and is evidently dwindling ; in the 

 more advanced foetus of the Mahiinadi specimen it had alto- 

 gether disappeared. 



On opening the abdomen of the foetus the greatly distended 

 spiral gut is seen lying to the right *, and the left lobe of the 

 liver to the lelt *. Wa stomach is small and empty and is 

 pushed up beneath the ])ectoral arcli. 



The small short duodenum, which is guarded at the pylorus 

 by a stout valve- like fold, is, like the anterior part of the 

 spiral gut, full of coagulated lumps of the uterine secretion. 

 The posterior three-fourths of the spiral gut is stuffed with 

 viscid, grumous, bile-stained matter. 



The rectum is sharply constricted off from the spiral gut 

 and looks like a solid cord ; dorsal to it lies the rectal gland 

 in a fold of mesentery common to it and the testes, to which 

 last it is intimately adherent. 



The liver is of large size and perfectly colourless ; the 

 spleen is also large. 



The left testis is several times larger than the right, 

 perhaps because the pressure of the distended spiral gut has 

 hindered the growth of the latter. 



The external gill-slits are closed ; their anterior edges are 

 finely pectinated. 



On laying open the capacious pharynx the wide internal 

 orifice of the spiracle is displayed. It lies in the same plane 

 with the branchial clefts proper, and symmetrically with them, 

 so that its homodynamy with them is of diagrammatic plain- 

 ness, and it difl'ers from them chiefly in being widely open, 

 while they are closed by the close approximation of the 

 branchial bars. 



It only remains further to remark, concerning the foetus, 

 that while its generic and subgeneric characters are quite 

 distinct, it has not yet acquired its full specific characters. 

 Except for a large centro-dorsal boss surrounded by a few 

 small tubercles its skin is quite smooth ; its tail-spine is 

 well developed, but entirely sheathed in skin. Its colour is 

 much like that of the adult, but lighter, being uniform brown 

 dorsally and olive-grey below except along the abdomen. 



* /. e. of the foetus. 



