385 Bulletin 5 15 



Saj' on Shells, &c. 37 



tive examination of its characters, exhibits its inseparable 

 connection with the family of Encrinites by the analogy of 

 its mode of support, its rectilinear sutures, and the general 

 form of its pelvis or basal portion. 



To the base is generally attached, the single superior 

 joint of the trunk or vertebral column ; this joint is short, 

 and is longitudinally^ divided by three sutures, which radiate 

 from a central foramen ; its inferior articulating surface is 

 orbicular, with numerous marginal radii, and the centre ex- 

 hibits the opening of the foramen ; at its junction with the 

 ossa innominata it is somewhat trilobate. The ossa innomi- 

 nata are of a rhomboldal form, sometimes pentagonal or 

 subquadrate. The pelvis has the same general form with 

 that of the Encrinus liliiformis, but the angles of the penta- 

 gon are much more acute, and those parts which Parkinson 

 denominates ribs, clavicles and scapulcz are not distinct. 



From the superior angle of each of the ossiculse of the 

 base, a stcho-e ascends, bisecting each of the interstitial spa- 

 ces, and is divaricated near the tip, so as to give to those 

 triangular spaces, a rhombric termination. Each of the five 

 outer foraminse, (of which one is invariably much the lar- 

 gest) is the common aperture of two tubes which penetrate 

 to the tips of the ambulacra, immediately beneath the su- 

 tures of those parts, and which are not visible but by dis- 

 section ; the central foramen is stellate. 



The peculiar adaptation of these various parts to each 

 other, may have permitted their independent movement, in 

 order that the animal might assume some form of expan- 

 sion ; but we are led to suppose that this motion could not 

 have been very considerable, from the relative situation of 

 the sutures. And I may further add, that, as we have no 

 direct proof that this animal did possess the power of ex- 

 panding, it may be, that the motion of its body was confined 

 to the protrusion of tentacula through the foramina, and per- 

 haps smaller ones through the pores of the Ambulacrse. 



This question, however, must remain for the solution of 

 future observers, who may have an opportunity to examine 

 them in situ, and of comparing together their different frag- 

 ments which may be discovered. All the specimens which 

 I have seen, about sixty in number, are in a 'perfectly similar 

 collapsed state. 



[A. J. S., ist Ser., Vol. II.] 



