406 Bashford Dean Memorial Volume 



raised into parallel ridges. This arm opens into the intestine by a protruding pyloric 

 aperture (Py. V.) which is furnished with distinct sphincter muscles." The pyloric 

 valve (Py. V.) figured by Hawkes (my Text'figure 73) appears symmetrical, thin-wailed, 

 slender and cylindrical — quite unlike any that I have observed, save that it protrudes into 

 the bursa. Possibly the drawing is inaccurate, since the valve appears too thin to be 

 provided with a sphincter muscle. In Heptanchus (Daniel, 1934, Fig. 123), as in Chlamy- 

 doselachus, the pyloric valve projects as a well-defined circular band into the bursa. 



THE BURSA ENTIANA 



In Chlamydoselachus, as in sharks generally, the middle intestine or duodenum is 

 short; as in certain other elasmobranchs, it is expanded to form a thin-walled sac, the 

 bursa entiana (Text -figure 72, h. e.). In Chlamydoselachus the bursa entiana is shaped 

 somewhat Hke the human stomach, but the orientation is difi^erent. Superficially, it 

 would resemble the human stomach if the latter were reversed end-for-end and rotated 

 so that the greater curvature would Ue to the right and dorsally. In my three specimens 

 the amount of distention of the bursa varies greatly, so that the dimensions recorded 

 here do not give any accurate information as to what the relative size would be if the 

 structures were measured under identical conditions. 



In my specimen No. I the bursa entiana is moderately distended and has moderately 

 thick walls; its condition is probably typical. Measured from the first coil of the spiral 

 valve to the apex of the pyloric valve, its length is 33 mm.; but after including the total 

 extent to which the bursa overlaps the pylorus, the length is 39 mm. Its greatest trans- 

 verse diameter is about 14 mm. Its walls are very thin (less than 1 mm.) at the cephalic 

 end, but toward the caudal end the thickness increases gradually to almost 2 nam. at the 

 junction with the valvular intestine. 



In specimen No. II the bursa is greatly contracted. Measured from the villosities 

 on the inner surface of the cephaHc end of the valvular intestine, to the apex of the 

 pyloric valve, its length is 20 mm. Since the bursa overlaps the pyloric valve for a distance 

 of 14 mm. on one side, its total length is 34 mm. Its greatest transverse diameter is 

 about 10 mm. The thickness of its walls ranges from 1 mm. at the cephalic end to 3 mm. 

 at the caudal end. 



In specimen No. Ill the bursa is greatly expanded. Its length, measured from the 

 cephaHc end of the spiral valve to the apex of the pyloric valve, is 40 mm. After in- 

 cluding the extent to which the bursa overlaps the pyloric valve, the total length is 

 46 mm. The greatest transverse diameter, which is near the caudal end, is about 18 mm.; 

 near the cephaUc end the transverse diameter is about 10 mm. The wall is everywhere 

 less than 1 mm. thick. 



In the lining of the ventral side of the bursa entiana in specimen No. I there is 

 a pocket (shown by a dotted outHne in Text-figure 72) about 10 mm. long, opening caudad 

 into the lumen of the bursa. The opening is about 8 mm. v,ade and is situated about 



