1888.] NATURAL SCIENCES OF PHILADELPHIA. 381 



them. There is nothing else like them in any known crinoid. If 

 they are hydrospires, then they certainly do afford a strong illustra. 

 tion of the close alliance between Blastoids, Cystids and Crinoids. If 

 they are not hydrospires, we should like to know what they are. 



Enallocrinus is evidently very closely allied to Crotalocrinus. The 

 genus occurs at Dudley, England, whence we obtained specimens 

 showiuo; the arms better than the Swedish ones, but nevertheless our 

 material for the study of this type was by no means so satisfactory 

 as that of Crotalocrinus. The English specimens are all more or 

 less crushed, and do not throw much light on the structure of the 

 calyx. 



Angeliu's figures purporting to show the vault are imaginary, as 

 we have before shown. The only specimen in the Stockholm Muse- 

 um showing any part of the ventral covering has been sent to us for 

 examination, and we give two views of it (PI. XX, figs 5 t^). It 

 is somewhat abnormal, two of the rays being grown together in 

 such a way as to modify the arrangement of some of the plates. It 

 is one of the specimens from which it is supposed Angelin's figure 

 3a, PL VII was constructed. The insertion of the higher radials 

 upon the first radials is upon the same plan as in Crotalocrinus, es- 

 pecially the species shown by Angelin's PI. XVII, fig. 3a, and our 

 PI. XX, fig. 4, and from this, and what little we can see of the ventral 

 covering in the specimen above alluded to, we conclude that the 

 vault must have been constructed substantially like that of Crotalo- 

 crinus. 



We figure a flattened specimen from Dudley (PI. XX, fig. 6!l), 

 which shows the arrangement and bifurcations of the arms, but not 

 by any means to their full length. We have another set of arms 

 Avhich seem to have their filiform extremities nearly complete, and 

 from this we should infer that the specimen we have figured shows 

 but little over half the length of the arms. Figs. 61 and 6i illus- 

 trate the projections from the sides of the joints, in the same speci- 

 men. We consider them important characters, perhaps representing 

 the projections on the arms of Crotalocrinus, and indicating a tend- 

 ency toward the reticulate arm structure, which is the only well 

 marked distinction between the two genera. 



The specimen represented by Angelin's PI. XV, figs. 1, la, and 2, 

 as Enallocrinus assulosus, and which Dr. Lindstrom assui'es us is 

 correctly figured, represents in the reduced lateral connection of the 

 arm bases, and the presence of small interradials on the dorsal side. 



