NOTES ON THE FOSSIL CRINOID GENUS HOMOCRINUS 



HALL. 



By Edwin Kirk, 



Of the United States Geological Survey. 



The genus Homocrinus was defined by Hall in the second volume 

 of the Paleontology of New York. At that time the structure of the 

 type-species, H. parvus, was incorrectly given and, furthermore, 

 species representing two other genera were referred to Homocrinus. 

 It would appear that the genus Homocrinus as there defined by Hall 

 was intended as a sort of "catchall" for practically any Silurian or 

 Ordovician Inadunate. The idea seems to have been to erect a genus 

 comparable in spacious capacity to Poteriocrinus and Cyathocrinus 

 as they were loosely used at that day. In the third volume of the 

 Paleontology of New York, Hall referred still another species, scopa- 

 rius, to the genus. This species is probably genericaUy distinct from 

 any hitherto called Homocrinus by Hall. Under such conditions it is 

 no wonder that the greatest confusion has prevailed in regard to the 

 exact status of the genus. The confusion has not been lessened by 

 the work of subsequent authors, who instead of maintaining the first 

 species described as the type have chosen genotypes from among the 

 other species at one time or another referred to Homocrinus by Hall. 



As matters stand, we apparently have a choice between no less than 

 three type species. There is the original genotype (first species) 

 H. parvus; H. scoparius, which was chosen by Wachsmuth and 

 Springer (1879, p. 77); and, finally, H. cylindricus, which was made 

 the type species by Bather (1893, p. 101). It is possible, if not pro- 

 bable, that these three species belong to as many genera. Under the 

 circumstances our conception of the genus Homocrinus depends entirely 

 upon the choice of the genotype. 



Wachsmuth and Springer in their "Revision," because of the sup- 

 posed unsatisfactory nature of the two Niagaran species referred to 

 the genus, refused to consider either as the type species, choosing 

 scoparius which was described by Hall (1859, p. 102) instead. Bather 

 (1893, p. 101) objects to the choice of scoparius as the type-species 

 on the ground that the date of the genus under these circumstances 



Proceedings U. S. National Museum, Vol. 46-No. 2038. 



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