154 PROCEEDINGS OF THE ACADEMY OF [1890. 



shells. Heretofore this pheuomeuon has admitted of no direct causal 

 iuterpretation. 



Attachment to Crinolds. The adherence of gasteropods of the 

 genus under consideration to fossil crinoids was at first thought to 

 furnish conclusive evidence of the carnivorous habits of the Crin- 

 oidea ; and inasmuch as it was at that time considered that the aper- 

 ture in the vault was the mouth, this explanation seemed very plaus- 

 ible. Consequently the conclusion was very naturally reached that 

 the criuoid, when it perished, was in the act of devouring the raol- 

 lusk. jNIeek and Worthen^ appear to be the first to question the prev- 

 alent opinions regarding the intimate association of crinoid and 

 gasteropod ; and to suggest that the mollusk was, in all probability, 

 stationed on the echinoderm for a protracted period, perhaps even 

 for the greater portion of its life. But notwithstanding the fact that 

 the univalve was almost invariably situated over the ventral aper- 

 ture, and that this opening was recognized as the anus, these writers 

 do not seem to entertain for a moment the idea that the gasteropod 

 may have been nourished upon the refuse matter from the crinoid. 

 The latter view more recently has been preferred by Wachsmuth and 

 is now favorably received by other paleontologists. In every instance 

 of the several hundred specimens lately examined the calyptnean 

 covers the anal opening of the crinoid ; and, so far as observable, it 

 is always the anterior portion of the molluscan shell that is directed 

 toward the vault aperture. In those examples where the shell has 

 been removed its impression made on the ventral surface shows that 

 the anterior margin of the peristome was at the edge of the opening 

 in the dome — a .position that would have brought the mouth of the 

 mollusk directly over the anus of the crinoid. From an examina- 

 tion of the concentric markings made by the molluscan shell on the 

 vaults of Strotocrinus (Plate II, fig. 7) and some other genera, it 

 appears that the forward end of the Capulus was always stationary 

 at the margin of the dome opening ; and that, as the growth of the 

 shell continued the posterior portion was removed farther and farther 

 from the ventral aperture of the crinoid. 



The food of recent crinoids consists chiefly of animalcules and 

 microscopic plants and the living Calyptrseidse subsist on food of a 

 similar nature. From analogy it might be inferred that the food of 

 fossil crinoids and mollusks must have been like their modern rep- 

 resentatives. So far as the echinoderms are concerned there seems 



1 Proc. Acad. Nat. Sci., Phila., 1868, p. 340, e^ se,/. 



