202 The American Geologist. March, 1892 
REVIEW OF RECENT GEOLOGICAL 
LITERATUGE: 
The three following papers are extracts from-the Tenth Annual Re- 
port of the New York State Geologist, 1891. 
1. Notes on the genus Acidaspis, 13 pp.,3 plates. By J. M. CLARKE. 
In his revis‘on of Ac¢dasp7s and related genera the author adopts a. rela- 
tion towards the earlier work of paleontologists which it is to be hoped 
will be more generally followed. “To ascertain as far as possible from 
the descriptions by earlier writers, their intentions. The original diag- 
nosis may have been brief, all too brief to satisfy the present require- 
ments of our science, their illustrations insufficient or faulty, but it will 
not suffice to reject aname upon these grounds alone. ‘Too imperfectly 
described to be identified,’ is a decree which often veils an unbecoming 
aspiration after immortality unrelieved by an abiding conviction of the 
necessity and justice of making every effort to establish the results of 
another’s investigations.” ; 
Ceratocephala, Warder, is retained and defined. Barrande objected to 
the use of this name on the ground that a very similar name had been pro- 
posed earlier by de Candolle, Ceratocephalus. ‘ For us, however, the ex- 
istence of de Candolle’s term does not in the least affect the value of that 
of Warder, as the two words are different.” In this connection we will 
restate a pertinent question recently raised in an editorial on “ preoccu- 
pied names,” in the American Naturalist for July, 1891: “Ifa difference 
of two letters is not enough to preserve two names, it becomes a question 
how many letters will constitute diversity, and soon. * * * The fact 
is the changing of a name which differs by a single letter from another 
hame has no warrant in any rule or in common sense.” 
The author then gives the history of a number of related generic 
names which have more or less fallen into disrepute but are shown to 
have a sub-generic value. Ceratocephala is divisible into two sections; 
the first with (1) Odontopleura, Emmerich, (2) Ac¢dasp?s, Murchison (syn. 
Acantholoma, Corda), (3) Ceratocephala, Warder (syn. Trapelocera, Corda), 
and (4) Dicranwrus, Conrad; the second section with Selenopeltis, Corda 
(syn. Polycres, Ronault). A new sub-genus, Ancyropyge, is established on 
Aciduspis romingert Hall, with the generic relation nearest to Cerato- 
: cephala. 
The North American species of which sufficient is known for sub-gen- 
eric classification are arranged thus: Ceratocephala, Warder sensu 
stricto: C. goniata Warder (syn. Acédaspis danai Hall, A. idu Winchell 
and Marcy). Acédaspis, Murchison: A. anchoralis Miller=?? A. ceralepta 
Anthony, A. Tuberculatus Conrad. Odontopleura, Emmerich: 0. trenton- 
ensis Hall, sp., 0. parvula Walcott, sp., O. hallé Shumard, sp., O. crossota 
(Locke?) Meek, sp., O. o’nealli Miller, sp., 0. ortont Foerste, sp. 0. callicera 
Hall, sp., Dicranurus Conrad with hamatus Conrad. Ancyropyge, Clarke 
with rominger?. 
