1879.] NATURAL SCIENCES OF PHILADELPHIA. 303 



which Goldfuss made the tj'pe of Crotalocrinus. 4. C. quinquan- 

 gularis, which has been conceded to be a Poteriocrinus. As a 

 proof how indefinite was Miller's conception of the genus, it may 

 be noted that three of the four species are of distinct families, 

 while he himself places Poteriocrinus among the Semiarticulata, 

 and Gyathocrinus among the Inarticulata. 



G. planus is, therefore, the only species that need be considered 

 with reference to Gyathocrinus. The "pelvis" has the typical 

 saucer shape, with a subpentangular perforation. There are five 

 " costals," four of them hexagonal, the fifth with a truncated supe- 

 rior margin ; " scapulas" of similar form to those in Poteriocrinus., 

 having also a horseshoe-like impression, with a transverse perfo- 

 rated ridge for the reception of the first arm joint (brachial), and 

 which is succeeded by a cuneiform bifurcating plate. The arras 

 (or hands of Miller) bifurcate several times, and there are six 

 fingers to each division of the ray, which are all tentaculated on 

 alternate sides. Here again is mentioned a single (anal) plate 

 interposed between the radials or " scapulae," and this plate is 

 placed upon the truncate costal (basal). The description applies 

 well generically to a large number of species which have been re- 

 ferred to Cyathocrinus, differing, however, in the pinnulate (ten- 

 taculated) arms. Not one of those species has ever been found 

 with pinnulse, though we have examined with reference to this 

 point a large number of species, and some most perfect specimens, 

 in which the covering of the ambulacral furrow is beautifully ex- 

 posed all along the arm, and in which it seems certain that if they 

 had been provided with pinnulse, these organs would have been 

 preserved. A similar covering has been found, with slight modi- 

 fication, in three or four other genera of the Cyathocrinidae, but 

 never in species with pinnulse, and this suggests the idea that 

 they may not exist in those genera. We therefore consider the 

 presence or absence of pinnulse of generic importance, and do not 

 hesitate to say that if Miller's Cyathocrinus planus had pinnulse, 

 it cannot be classified with species in which these organs are 

 wanting; and we also feel assured, from analogy, that if this was 

 the case in G. jylaiius, it will be found to possess more than one 

 anal plate in the calyx, and prove to be a true Poteriocrinus. 



Miller figures three specimens of this species. Fig. 1 repre- 

 sents an entire specimen, with a piece of column and perfect 

 arms ; the arms branch off from the second brachial, and are 



