﻿Cephalopoda of the Cincinnati Group. 



253 



By an examination of the embryos, the siphons, the sutures, and 

 other features, the author formulates a series of orders and genera which 

 are simply appalling. There are enumerated in this paper no less than 

 eighty-three new genera, most of them formed on species of older genera 

 which differ in a few characteristics from their fellows. For example, in 

 regard to Orthoceras, which Professor Hall says* includes 323 species in 

 North America, Prof. Hyatt says he "has met with but two species in 

 North America, though doubtless others may exist, since the extreme 

 smoothness of the shell is easily destroyed." He thinks the generic term 

 should be restricted to "straight and comparatively smooth longicones 

 with simple septa and sutures. "7 He then makes five new genera based on 

 species of Orthoceras in addition to two previously made. Gomphoceras, 

 Cyrtoceras and Phragmoceras each furnish several new generic names. 

 Many of these seen to be founded on very insufficient characters, although 

 what should be considered a good character is a matter of opinion merely. 

 For example, Tetramoceras "includes Silurian species having four lateral 

 sinuses," which were previously referred to Phragmoceras. Hcxamcroceras, 

 "includes Silurian species having six lateral sinuses in their apertures," also 

 previously placed in Phragmoceras. Trimeroceras, Pcntamcroceras have re- 

 spectively, two, four and six lateral sinuses in addition to a median sinus, 

 all these having been previously referred to Gomphoceras, while this last 

 genus is restricted to the " straight and arcuate forms which have symmet- 

 rical T-shaped apertures.";, 1 ; 



It is an unfortunate tendency which many writers have developed to 

 establish new names on slight differences. It is reprehensible to make 

 new species on insufficient grounds, and still more unpardonable to estab- 

 lish genera. It is especially deplorable and common in palaeontology, not 

 only because of the fragmentary nature of the fossils, but because of our 

 limited knowledge of the modes of life, the geographical distribution, and 

 other facts which are invariably taken into consideration when living 

 organisms are concerned. 



*Pal. of N. Y., vol. V, part 2, (text p. 230. 

 f Page 275. 

 t Pages 277-78. 



