STRUCTURE OF THE CYSTIDEiE. 33 



originate in the sides and not in the centre of the ventral surface, 

 as in the Cystideae. 



Fig. 19. Epactocrinus irregularis (Wirtgen and Zeiler). 



3. In Pentacrinus captit-Medusce, the mouth, although combined 

 with the ambulacra! orifice, has a structure similar to that of the 

 Cystideae. This fact is pointed out by MM. Koninck and Le Hon in 

 their magnificent work upon the Crinoids of the Carboniferous rocks 

 of Belgium.* The observations were made upon a fine specimen 

 captured by a fisherman in the harbor of Moule, Island of Guade- 

 loupe, and sent by Dr. Duchassaing to M. Michelin. The following 

 is Dachassaing's description of the mouth: — 



"The mouth of the Eacrinite is surrounded by five lips, and can be seen only when 

 these five lips are opened. It then appears as a small round aperture about two lines 

 in diameter. The lips are not free, and can be opened to the extent of about three 

 lines. They are adherent to the five furrows which departing from the commissure.s 

 are prolonged to the circumference of the disc. Mastication is effected, not by the 

 mouth, but by the lips, which are armed to that effect with small stiff spines. As to 

 nourishment, I found the debris of small crustaceans." 



Upon the above extract, MM. Koninck and Le Hon make the 

 following remarks : — 



" It is perhaps well to observe here, that it results from the remarks of M. Duchas- 

 saing that what he calls lips are veritable triangular valves, hard, and armed at 

 their points and internal surfaces, and designed to hold and crush Crustaceans ani3 

 other animals upon which the Pentacrinus appears to feed. 



" They have exactly the same form as the ossicles which in the Cystideae cover the 

 aperture which L. von Buch has considered as an ovarian orifice. 



" We have no doubt that the illustrious palseontologist whose recent death science 

 deplores, did not recognize the true function of that opening. We are persuaded that 

 it served the same purposes as those which have been observed iu Pentacrinus. Our 

 conviction is so much the more profound that we have never been able to discover upon 

 the triangular valves of the Cystideas the least trace of a perforation, and that those 

 which cover the mouth of Pentacrinus offer nothing more. 



" It would be besides very extraordinary that these calcareous plates whose position 

 and form are perfectly identical in these animals, belonging to the same class, should 



* Recherches sur les Crinoids du Terrain Carbonifere de la Belgique. Par L. Do 

 Koninck et H. Le Hon, 1844 ; page 33 et seq. 



C 



