31 



tangular aperture formed by the truncated ends of the joints of the pelvis, at the 

 bottom of the funnel-shaped abdominal cavity, we observe the entrance to the 

 alimentary canal, protected by the sphincter muscle of the superior enlarged 

 columnar joint. 



To the general idea thus obtained of the organization of this animal, it 

 should be added that the appearances presently to be stated indicate two other 

 important particulars; FIRST, that the upper-part of the funnel-shaped cavity 

 containing the viscera, was protected externally by series of small plates leaving 

 a central opening for the mouths, and SECONDLY, the existence of lateral open- 

 ing on the exterior of the circumference of the body, possibly forming the 

 mouths of the ovaries. The appearances leading to this conclusion are, viz. 



We often trace several nearly wedge-shaped four, five, or six-cornered plates 

 (PL. in. fig 2. PL. 6. fig. 2. Q.) interposed between tl>e angles of the two second 

 costals, scapulae, and first and second arm joints,in aline with the lateral surfaces 

 of the scapulae; and in this part sometimes forming two series. These I con- 

 sider as analagous to the pectoral plates of the pentacrinites, actinocrinites, &c. 

 and thence conclude that this animal had also an external integument over 

 its abdominal cavity, rendered stronger by the interposition of numerous 

 minute adhering plates, which also spread over the excavated or channelled 

 portion of the arm joints, finger joints, and tentacula, as is the case in PEN- 

 TACRINUS CAPUT MEDUSAE, in treating of which this structure will more fully be 

 explained. That the abdominal cavity had, in this animal, really such a cover- 

 ing, is rendered further probable by the occurrence of round balls of clay rest- 

 ing sometimes within it, and evidently formed as casts in its interior; (which 

 are erroneously noticed by TOWNSEND in character of MOSES, vol. r. p. 269, 

 as opercula) of these the upper surface seems to have moulded against some 

 such covering. 



I shall now state the appearances, which I think, may possibly be consi- 

 dered as indicating the mouths of the ovaries of this animal. In or between 

 the lateral surfaces of the joints of the pelvis and the insertion of the first costal 

 joints, we may frequently trace a violent contraction, rendering this part of the 

 animal subpentangular (PL. vn. fig. 12.) and in thesame parts we also observe 

 more or less elevated tubercles, (PL. vn. fig. 7. II. 12. 13 ) having a central per- 

 foration, which in one instance I have traced (fig. 7.) to pass through the joint of 

 the pelvis into the space between it and the costal joints, extending perhaps 



