The Anatomy of Chlamydoselachus 



459 



loosely laid one upon another, those in the posterior section, or stem of the pipe, running 

 transversely, and those of the anterior section being longitudinal. 



Behind the ventricle, in the partition, between the peritoneum and the pericardium, there 

 is a spongy mass of dark tissue an eighth of an inch in thickness. 



Giinther (1887) had available for examination three well-preserved specimens of 

 Chlamydoselachus. His drawings, illustrating the external form of the heart and the 

 configuration of the valves of the conus, are reproduced as my Text-figures 102a and 102b. 

 Giinther gives no general description of the heart, but it will be noticed that his figure 

 confirms Carman's (1885.2) statement con- 

 cerning its form. 



Ayers' (1889) Fig. 2 (reproduced as my 

 Text-figure 105, p. 462) portrays the heart of 

 Chlamydoselachus in sectional view, and the 

 drawing appears to be semi-diagrammatic. 

 Therefore this figure does not give us much /'^ 



information concerning the form of the heart 

 in his specimen. His description (p. 194) of 

 the conus arteriosus follows : •^' 



% 



The conus arteriosus forms a thick 

 spindle-shaped trunk about an inch long and 

 one-fourth of an inch in diameter. It is pro- 

 vided with six rows of valves, all of which 

 are quite small, except the anterior set of 

 three, which are large, tridentate, and 

 formed of a white tough tissue of a cartilag- 

 inous consistency. 



Text-figure 102. 



Heart of Chlamydoselachus : A, in ventral view ; B, 



conus arteriosus opened longitudinally to show the 



arrangement of the valves. 



r, right atrium; !, left atrium. 

 After Gunther, 1887, Figs. 7 and 8, pi. LXV. 



My observations do not entirely agree with those of Garman and Gunther regarding 

 the proportions of certain parts of the heart. In my three specimens (from the fourth 

 specimen the heart had been removed) the conus arteriosus is indeed long, as in Garman's, 

 Giinther's, and Ayers' specimens; but the ventricle, even when empty, is larger than it 

 appears in the figures by Garman and Giinther, and the si2,e of the atrium is variable. 

 Text-figure 103a is drawn from my specimen No. Ill in which the ventricle (v.) is moder- 

 ately distended with blood. The atrium (atr.) is empty, but in its flattened condition 

 it retains a smoothly rounded outline, as shown in the figure. The size of the atrium is 

 somewhat exaggerated due to its flattened condition; nevertheless, the atrium of this 



Text-figure 103. 

 Hearts of two specimens of Chlamydosel- 

 achus, in ventral view, one-half natural size: 

 A, drawn from No. Ill; B, from No. II. 



atr., atrium; ecu., common cardinal vein; co., conus 



arteriosus; s.v., sinus venosus; v., ventricle. 



Drawn from specimens in the American Museum. 



