A XEW FOSSIL Cr.IXOID GENUS KIRK 515 



form cup and depressed base of D'lnofoo'inuH at once sei)arate tlie 

 oeiuis from ^Voo(lo(■r/nuH witli its turbinate cup and prominent IBB. 

 Dmofoc/'hnt.^ resembles very young- Zeacriuus^ :ind, although one 

 would not place them in the same family, the pr()ba})ility is that they 

 are nearly related. Although many of the crinoid genera associated 

 with D'niotocr'tnus carry on upward into the prolific crinoid faunas 

 of the higher Chester, neither Dhiofocihim nor any form clearly 

 derivative fi'om it has been found so fai*. D'nrotocriiius seems nearly 

 I'elated to DascJocrinus and may be ancestral to it. 



Remarks. — I have referred Pofertocrinus salteii Worthen to 

 Dinotoei'/iiKs. The figure is poor, and I have not examined the 

 type, but there is a great similarity to young Dhtofoerrniis, and there 

 does not seem to be any other Chester genus to which it is referable. 

 Agasslzocrhius hemisphericns "Worthen may fall here, but well-pj-e- 

 served crowns from the Chester of Illinois with similar dorsal cups 

 do not agree in arm structure. (';iathocihi>te!< roetneH Troost is a 

 Dinofocrhius. Troost's type is a young s])ecimen in a very poor 

 state of preservation. Wood (1909, p. 86) lists Troost's species as 

 a. synonym of ScaphiornnuK kwrtsvillae Worthen. This cannot be. 

 If Worthen's figure can be relied on, his species is quite distinct 

 and probably referable to DfMrioej-!/ti/-'<. The horizon of Diiiotocrmus 

 foemen is uncertain. Judged from the lithology of the matrix, it 

 seems ])robable that the specimen was collected from the Gasper. 

 This is the horizon from which most of the crinoids were taken in 

 the early days. 



DINOTOCRINUS COMPACTUS, new species 

 Plate 6?> 



Of this s])ecies there are some S,") crowns available for study, the 

 net result of collections made during many field seasons by Carl 

 liominger. Charles Wachsmuth and his wife, and me. The specimens 

 range in size from 13 to 40 millimetersi in height. 



With the arms erect the crown is subcylindrical. with closely ap- 

 |)ressed rami, except in the jiosterior inter-ray. The crown is notable 

 in the relative shoi'tness and stoutness of the rami. 



The dorsal cup is cyathiform, with a sharply truncate l)ase. The 

 ratio of height to breadth is approximately 3:8. The IBB are 

 closely united in a pentagonal plate that extends well beyond the 

 column and lies entirely within the basal depression. The basals 

 are large, tumid, and form the base of the cup as seen in lateral 

 view. The radials are wider than high. The articulating suture is 

 linear and slightly gaping, extending the full width of the radial. 

 The radianal is large, resting below on the post and r post BB and 

 penetrating faii-lv deeply between them. The contact with the pos- 



