456 Bashford Dean Memorial Volume 



In specimen No. II the condition of the canals (Text-figure 100a) is most like that 

 described for other elasmobranchs, though some differences are obvious. On the anterior 

 surface of the posterior pericardium (p.p), close to its dorsal border, there is a large opening 

 (c.) leading into a shallow cavity. The width of the cavity (and of its opening) is about 

 12 mm.; its depth is only about 3 mm. This cavity, which I shall call the pericardio- 

 peritoneal sac, represents the fused portion of the two canals (r.p.c. and l.p.c), which 

 open into it by apertures about 4 mm. in diameter. The canals were probed. Each is 

 about 4 mm. wide when collapsed, and is about 20 mm. long; the walls are very thin. 



Text-figure 100. 

 Pericardio-peritoneal canals of Chlamydoselachus, leading from the pericardial 

 cavity (above) to the peritoneal cavity (below); ventral views, natural sise. 



c, common opening of the canals into the peritoneal ca-inty; d.p., dorsal pericardium; l.p.c, left 

 pericardio-peritoneal canal; es., esophagus; p.p., posterior pericardium; p.p.s., pericardio-peritoneal 

 sac formed by the fusion of right and left canals; r.p.c, right pericardio-peritoneal canal. 

 A is drawn from specimen No. II in the collection of the American Museum of Natural Historj'; 

 B, from a specimen (No. IV) lent by Dr. E. Grace White. 



The canals pass dorsad along the posterior surface of the pericardial wall to reach the 

 esophagus (es.), then caudad along the ventral surface of the esophagus, dorsal to the 

 Kver, to open by wide crescentic apertures into the peritoneal cavity (Text-figure 100a). 



In my specimen No. I, conditions are practically the same as in No. II save that the 

 pericardio-peritoneal sac is about 6 mm. wider than its opening into the pericardial 

 cavity, and that the right pericardio-peritoneal canal is closed at its posterior end. 



In specimen No. Ill the common aperture and the pericardio-peritoneal sac are 

 much the same as in specimen No. II, but their situation on the posterior wall of the 

 pericardial cavity is a Httle further ventrad — not so close to the dorsal border as in the 

 preceding specimens. Thus the paired canals must pass a Httle further dorsad in order to 

 reach the esophagus. The canal on the right side is only 5 mm. long and does not reach 

 the esophagus. The canal on the left side is 10 mm. long and turns posteriorly upon 

 reaching the esophagus. Both canals are closed at their posterior ends. 



