20 BULLETIN OF THE 



left at the cloaca showed one of the ducts greatly distended, possibly 

 with young that had hatched within it. Only one of the tubes had 

 been in use. In Fig. 2, Plate XIX., the oviduct that had not been 

 expanded is shown at one side (ov), the other having been slit open with 

 the cloaca to show internal arrangement. 



The Nidamcntal Gland. 



Plate XX. Fig. C. 



The gland consists, in appearance, of two thick plates of laminated 

 structure. The plates are longer and thicker in the middle, and 

 shorter and thinner at each side. The short sides have been applied 

 and united ; this leaves an acute point descending from the thicker por- 

 tion on the inside of the tube. The insides of the walls are crossed by 

 minute stria), between the laminaj, which appear transverse, but in 

 reality are spiral and ultimately — following the outlines of the anterior 

 or posterior borders — terminate, forward or backward, in the longitu- 

 dinal folds of the tube itself. The inner edges of the lamina) are set 

 with minute pores. Near the middle of its length there is a deeper 

 transverse groove. This is crossed by the laminae without change in 

 their directions on its account. The plates are not distinct from each 

 other through the whole of their length ; branches frequently cross 

 obliquely from one to the other. The bottoms of the grooves between 

 them have closely-set transverse partitions. The walls of the gland 

 are thicker anteriorly ; tliey begin abruptly, or even extend a little in 

 front of their points of attachment to the tube. The appearance is 

 such as would result from twisting the inside walls of the duct very 

 closely for a short distance. In this we have a hint as to the origin of 

 the gland. The distended condition of the oviduct is the only reason 

 for supposing the eggs to be hatched before extrusion, after the shells 

 have been supplied. 



The Intestines. 



Plate XrX. Figs. 3, 3. 



What remnants of the intestines were left show that the shark pos- 

 sesses a spiral valve in the intestine and a cajcal pouch behind the valve. 

 The intestine {int) opens into the cloaca {cl) behind the openings of the 

 oviducts. The ureters unite before reaching the cloaca, into which they 

 empty by a single aperture (ua), Plates XII. and XIX. In this speci- 



