1888.] NATURAL SCIENCES OF PHILADELPHIA. 365 



best known English specimens, in the British Museum and other 

 collections, and by considerable effort succeeded in obtaining some 

 excellent material for more detailed study, both from England and 

 Sweden. Besides this we have enjoyed the unexpected privilege of 

 studying a number of the original specimens used by Angelin. For 

 this we are indebted to Dr. Gustav Lindstrom, Curator of the 

 Palisontological Department of the National Museum at Stockholm, 

 who on being informed of our perplexity regarding this genus, upon 

 his own motion, sent us these and other specimens, with liberty to 

 study them at our leisure; and also furnished us most important 

 information in the way of drawings and observations upon other 

 specimens. It was an act of thoughtful kindness for which we find 

 it difficult to adequately express our gratitude, and if this paper 

 shall be found to be of any value to our fellow naturalists, it will be 

 in a very large measure due to the facilities thus generously afforded 

 us. 



In the Revision of the Palseocrinoidea, Part III, pp. 140-143, we 

 referred Crotalocrinus and Enallocrinus to the Articulata, and at 

 various places (pp. 18, 19, 56, 64, 65) based some of our arguments 

 as to the character of this suborderHipon the supposed structure of 

 these two genera. On pages 18 and 19 of Part III, we stated that "In 

 the Crotalocrinidae, which include Crotalocrinus and Enallocrinus, 

 the whole ventral surface, in what appear to be the best preserved 

 specimens, is composed of strong, convex plates, without definite 

 arrangement. In these specimens there is no central plate, nor 

 proximals, nor traces of ambulacra (Icon. Crin. Suee., PI. VII, fig. 3a; 

 PL VIII, figs. 6, 7, and PI. XXV, fig. 2.); there are, however, other 

 figures of Angelin, apparently of a closely allied species (ibid. PL, 

 XVII, fig. 3a), in which the plates paving the ventral surface are much 

 more delicate, and consist of a central plate, large proximals, and sev- 

 eral rows of covering pieces, without the intervention of either anam- 

 bulacral or interradial plates. It would be difficult, with the utmost 

 stretch of our imagination, to recognize in the former figures either 

 proximals or central piece, which, as admitted by Carpenter, are 

 present in all these crinoids, and we think there can be little doubt 

 that the two sets of figures represent different parts of the animal, 

 the one the disk, the other the vault, and that the one covered the 

 other. A similar opinion was evidently entertained by Zittel 

 (Handb. d. Palaeont. I, p. 357), who stated that Crotalocrinus pos- 

 sessed five 'grosse Orali:)latten, bald unter der Decke, bald ausserlich 



