ART. 15 THE FOSSIL CRINOID GENUS VASOCRINUS KIRK 7 



such plates. If one will attempt to reconstruct a dorsal cup from 

 oeneric diagram Figure 3 he will find that an impossible crinoid struc- 

 ture results. Precisely such a structure is indicated in Figure 3^^, 

 and as I first saw it the specimen itself had the same curious group- 

 ing of malformed plates outlined on the surface in ink. What Lyon 

 actually did was to coalesce 1. post, li with part of anal x. His 

 large single anal plate and its remarkable shape was brought about 

 by the coalescence of R A with part of anal x, part of r. post. R, 

 part of post. B, and all of r t. 



Were specimen 3a the only individual referable to Vasocrinics 

 valens, I would reject the species as genotype, despite the fact that it 

 is the first species described and evidently was Lyon's own choice. 

 Lacking as it does the essential posterior interradius, the status of the 

 genus would forever be in doubt. To choose F. sculptus would be 

 unwise. F. smiJpfus shows structural features sufficiently at variance 

 with those of valens to raise a suspicion that when well preserved 

 crowns are available for study the two species might not prove con- 

 generic. Fortunately the matter is simplified by the discovery that 

 specimen 36, used by Lyon in his diagnosis of the genus and in the 

 description of F. valens^ can well be referred to that species. It can 

 not by any chance be conspecific with specimen 3c-e. On the other 

 hand, close comparisons of specimen 36 after being freed from the 

 matrix with specimen 2>a as well as other imperfect specimens clearly 

 consi^ecific with 3a, but of smaller size, indicate the propriety or 

 rather necessity of referring specimen 36 to V asocrinus val-ens. 

 P^irtliermore, a well-preserved tlieca, clearly congeneric with valens. 

 has come to light that not only shows all the plates of the dorsal 

 cup, but has a well-preserved tegmen. With specimens 3a and 36 

 united under one species, most of our troubles are over. Now, the 

 generic description of Vasocr^inus and the description of F. valens 

 are in complete harmony with the structures of the specimens referred 

 to it — that is, the structure as interpreted by Lyon. The proper 

 course, then, seems clearly to be to make Vasocrinus valens the geno- 

 type, transferring to the species specimen 36. 



Genus VASOCRINUS Lyon 



In drawing up the formal definition of the genus Vasocrinus the 

 type species F. valens Lyon and the closely allied F. turbinatiis^ 

 new species, have been used. F. sculptus Lyon may be congeneric 

 and so far as its structures are known can not well be separated from 

 the genus. Its variations in structure from the typical forms have 

 not, however, been incorporated in the generic description. Two new 

 species from the Middle Devonian, one from the Hamilton of New 

 York and the other from the Traverse formation of Michigan, are 



