156 PROCEEDINGS OF THE ACADEMY OF [188G. 



been accepted by Wetherby and Williams, but ignored b}'^ S. A. 

 Miller and Prof. Worthen.' 



Extensive collections made by us during the last two years, 

 enable us to give additional information respecting these divi- 

 sions. Farisocrinus proves to be not only a good genus, but, 

 moreover, is a Cyathocrinoid, having no pinnules. Pachylocrinus 

 is closer allied to ZeacrinuH than to Poteriocrinus, and is proba- 

 bly identical with Philocrinus. De Koninck described this genus 

 with a monocyclic base, and the calyx strictly pentahedral, but 

 from appearance it had underbasals and az3'gous plates, and is 

 identical with Pachylocrinus. We have redefined Scytalocrinus 

 and Decadocrinus, which should both be ranked as subgenera 

 under Poteriocrinus, and likewise Scaphiocrinus. 



Mr. Percy Sladen, in a paper " On the genus Poteriocrinus and 

 allied forms " (read before the Geol. and Polyt. Soc. at Yorkshire 

 in 1877), separated the English Carboniferous Poteriocrinites 

 into four groups : Poteriocrinus^ Dactylocrinus, Scaphiocrinus 

 and Zeacrinus. To the typical form he referred: P. crassus, P. 

 spissus, P. conicus. P. plicatus^ P. impressus, P. radiatus and P. 

 quinquangularis. We agree with him as to the first four species, 

 but we think the last three are C^^athocrinidffi and should be 

 referred to Parisocrinus. Mr. Sladen, unfortunatel}^ figured 



' S. A. Miller, in the 2d Ed. of his Catal. of Pal. Poss., called them 

 "subgenera of doubtful utility." Prof. Wortheu gives the following rea- 

 sons for refusing their acceptance (Bull, i, Illinois St. Mus. Nat. Hist., p. 

 4): "First, I see no beneficial result that is likely to come from cumbering 

 the nomenclature of paleontology with such terms, and secondly, because 

 any proposed subgeneric formula that groujjs together such diverse forms 

 as Zeacrinus maniformis Y. and Sh., and Poteriocrinus Biselli Worthen, 

 can be of no practical advantage in the study of this group of Criuoids, and 

 hence, until some satisfactory generic cliaractei's can be pointed out by 

 which they may be separated, it seems advisable to include them all under 

 the generic name originally j)roposed by Miller for them." If our good 

 friend had read our paper more carefully, he would have observed that we 

 proposed our six subdivisions of Poteriocrinus with the distinct statement 

 that we "scarcely deemed the characters upon which they are based suffi- 

 ciently important even for subgeneric separation," and that we alluded in 

 detail to the difficulty of referring the " Zeacrinus " maniformis to any of 

 the sections. In proposing these subdivisions, however, we only followed 

 the suggest'on of Meek and Wortheu in 1869 (Proc. Acad. Nat. Sci. Phila., 

 p. 138 and note), where, after defining Scaphiocrinus, Zeacrinus and Ccdio- 

 crinus as subgenera under Poteriocrinus, they add, under the head of Scaphio- 

 crinus : "The group, however, has been extended by Prof. Hall and others 

 so as to include species presenting all the characters given above, and might 

 be divided into several sections, distinguished from each other and from the 



