474 PROCEEDJ-NQS OF THE ^'ATIONAL MUf^EVM. vol.46. 



would have to be altered from 1852 to 1861, "thus predating the name 

 by Eichwald's appHcation of it to Hoplocrinus dipentas, a consequence 

 that Wachsmuth and Springer seem to have overlooked." It is to be 

 noted that the other two species referred to Homocrinus by Hall 

 in his original description of the genus are ignored by Wachsmuth and 

 Springer when choosing their genotype. These two species are 

 Poteriocrinus altematus Hall and P. gracilis Hall, which were described 

 in the first volume of the Paleontology of New York. They have 

 since been referred to the genus Dendrocrinus by Wachsmuth and 

 Springer. An examination of Hall's diagnosis of Homocrinus makes 

 it evident that the two species cited above were definitely provided 

 for m the new genus. This is clearly shown in the description of the 

 arms, which are stated to be "simple or bifurcating," the arms of 

 parvus being simple. If Homocrinus parvus and H. cylindricus were 

 to be ehminated as unsatisfactory, the other species could not. This 

 would make the genotype of Homocrinus an Ordovician Inadunate 

 now referred to the genus Dendrocrinus. If the Ordovician species 

 be congeneric with the type species of Dendrocrinus this genus must fall 

 into synonymy with Homocrinus, 2ls the description of the latter genus 

 precedes the diagnosis of the former in the second volume of the 

 Paleontology of New York. 



Bather in choosing cylindricus as the type species set aside parvus, 

 the first species described by Hall under his new genus, as being based 

 on unsatisfactory material and having been insufficiently described; 

 cylindricus and scoparius he considers congeneric. As a matter of fact, 

 the structure of parvus may be worked out in great detail. H. cylin- 

 dricus, on the contrary, is represented by a not overly well preserved 

 dorsal cup. This does not permit of exact determination, and although 

 its genetic affinities are fairly clear, its use as a genotype is bound to 

 result in uncertainty of generic de&iition. As regards the accuracy 

 of the original descriptions of the two species there is Uttle choice. 



Such a case brings home to us most forcibly the necessity of a 

 definite ruhng restricting the powers of subsequent writers in revising 

 the original author's conception of his genus. The question, after all, 

 should be quite as much one of fairness to the original author as one 

 of convenience to subsequent workers. In formulating such a rule it 

 seems to me that paleontologists need not be governed by exactly the 

 same regulations as other zoologists and botanists. In paleontology 

 the type material under normal conditions is indestructible, and in 

 the majority of cases has been preserved. So, too, as a rule, hava the 

 descriptions and figures been adequate, and the geological horizons 

 and localities noted with a sufficient degree of accuracy. Generally 

 the original material is to be had if one be wilhng to spend the time 

 looking for it. If it be not accessible, authentic material is frequently 

 at hand coming from the same locahty and horizon. Such being 



