CRUSTACEA. 
53 
Dalmanites (Odontocephalus) bieidus. 
PLATE XI li, FIGS. 22-25. 
Dahiiania bifida, Hall. Descr. New Species of Fossils, etc., p. 63. 1861. 
Dalmania bifida, Hall. Fifteenth Kept. N. Y. State Cah. Nat. Hist., 91. 1862. 
Compare Dahna7iite.s (Odontoceplialm) JEgeria, H.all ?, Meek and Worthen. Geology of Illinois, vol. iii, 
p. 417, pi. X, fig. 4 a, b, c. 1868. 
The pygidium only of this species is known, and while presenting in general 
features a similarity with that of Dalmanites selenurus it is characterized by the 
following,persistent points of diiEference, viz.: (a) the axis bears eight annula- 
tions; (b) the pleurm show seven annulations with indications of an eighth; 
(c) the caudal extremity is narrow and considerably produced, making the post- 
axial area very conspicuous; (d) the caudal spines are close together, short, 
stout and parallel. The Dalmanites ^geria? of Meek and Worthen {loc. cit.) 
appears to be more closely allied in the character of the terminal spines of the 
pygidium, to D. bifidus. The cephalon which is referred by these authors to 
the same species as the pygidia, is represented in their figure as having a frontal 
border with a row of elongate perforations which do not extend to the margin. 
If this character of the specimen is accurately shown, there can be no doubt 
that this form is widely different from any species of Odontocephalus known from 
formations in the State of New York. 
Distribution. Upper Helderberg group. Corniferous limestone; Phelps, 
Ontario county ; Lime Rock, Genesee county ; Columbus, Ohio. 
Dalmanites (Odontocephalus) -dEoERiA. 
PLATE XI B, FIGS, 1-11. 
Dalmania JEgeida, Hall. Descr. New Species of Fossils, etc., p. 57. 1861. 
Dalmania JEgeria, Hall. Fifteenth ReiM. N. Y. State Cab. Nat. Hist., p 85. 1862. 
Dalmanites JEgeria, Hall. Illustrations of Devonian Fossils, iil. xii, figs. 3-6, 8-11. 1876. 
This species in its general features and broader details is so closely similar to 
D. selenurus, that the description of that species will serve for this one except 
in the following particulars; in D. jEgeria (a) the body is rather more slender, 
tapering more rapidly backward; (b) the frontal denticiilations are eleven in 
number, one central and five on either side, the terminal ones standing opposite 
the lateral extremities of the frontal lobe of the glabella; (c) the genal angles are 
