ol<) The American Geologist. November, i892 
Mr. Tail' finds iu the Fredericksburg divisiou, associated with Gr//ph(i'a 
pitrheri, they have uo henriiig on the strata which Mr. Marcou claims 
have uuimpeacliable evidence of .Jurassic age. He did in his original 
paper represent the wiiole of Pyramid mountain as Jurassic, above liis 
stratum E, but he has not claimed, so far as we have learned, that any 
strata containing the Fredericksburg or Washita fauna are of .Jurassic 
age. In Pyramid mountain these upper strata afPorded him no fossils, 
and his assignment of them to the .Jurassic was based apparently largely 
on topographic considerations. Mr. Cummins' argument can only apply 
to these upper strata, and he seems to have proved, by the aid of Mr. 
Taff, who has defined the position of his fossils more exactly, that they 
are not in the .Jurassic. 
By this report, of which otlier cha])ters, though perhaps eciually mer- 
itorious, no special mention can be made here, it is seen that the Texas 
survey is making substantial and even rapid progress in the field-work, 
■and is elucidating the geology of a large and interesting and difiicult 
section of the union. The ensemble of the volume is very creditable, 
the illustrations and maps are excellent. We only notice occasionally 
in Mr. Cummins' report, an ungrammatical use of the word " strata," 
Avliich cannot be wholly the fault of the proof-reader. 
- _ Some Neio Hperiex and New Structural Farts of Fossils. J-5y S. A 
Miller and Ciiahles Faber. (.Jour. Ciu. Soc. Nat. Hist., Vol. xv, No 
2, July, 1892.) In this paper the authors describe as new eight paleozoic 
species of fossils under names and from rocks as follows : Modiolopsis 
corrugata, M. longa, M. sulc<it((, Orthodcsma mundura, Protoscolex magnus, 
and Cyclocystoides cincinnatiensis, from the Hudson River group of 
Ohio, Jloloeystiies affinis from the Niagara gi'oup of Indiana, and Avicu- 
lopect(fn germanus from the Coal Measures of Kentucky. Besides, the 
under side of a specimen believed to belong to Agellacrinus pileus is de- 
scribed and new details of structure are brought out. The paper is ac- 
companied by a plate containing eighteen figures. 
A critical examination into the merits of the new forms seems to show 
a too great confidence of the authors in the ol)viousness of the peculiar- 
ities of their species. We luiss, namely, sutticient comparisons with re- 
lated species, a criticism that may justly be made on most of Mr. 
Miller's really valuable previous productions. As a rule we regard it as 
not onlj^ good practice but almost a necessity for the author of a new- 
species to supplement his description with full comparisons with related 
species, since these are a great aid in the always difiicult task of identi- 
fication. For instance, it would have been most desirable to learn from 
the authors just in what respects their 3Iodiolopsis corrugata differs from 
the similarly marked M. plioladiformis Hall, and M. capax Miller. As it 
is, we must confess that we are strongly inclined to doubt that these 
three names stand for as manj^ good species. 
M. longa agrees in a general way with M. ohlongn and M. tiubparalleJa 
of Ulrich, hut seems to be even more elongate and with the point of 
greatest convexity nearer the posterior end. On the other hand, there 
