CRUSTACEA. 53 



Dalmanites (Odontocephalus) B1FIDUS. 



PLATE XI B, FIGS. -'-' 25. 



Dalmania bifida. Hall. Descr. New Species of Fossils, etc . p. 63. 1861. 

 Dalmania bifida. Hall, Fifteenth Repl N. "5 State Cab. Nat. Hist., p. 91. LS62. 



( lompare Dalmanites (0 lontoeephalus) . Egeria, Hall ?, Meek and Worthen. i reology of Illinois, vol. iii. 



p 117. pi. x. fig. I a, b, c. 1S68. 



The i'YgidiuiM 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 difference, viz.: (a) the axis bears eight ambula- 

 tions; (b) the pleurae 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 JEgeria? 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) yEgeria. 



PLATE XI H, FIGS 1-11. 



Dalmania JEgeria, Hall. Descr. New Species of Fossils, etc., p. 57. 1861. 

 Dalinania ZEgeria, Hall. Fifteenth Rept. N. Y. State Cab. Nat. Hist, p 85. 1862. 

 Dalmanites 33geria, Hall. Illustrations of Devonian Fossils, pl. xii, figs. 3-6, 8-11. 1876. 



Tins 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. Mgeria (a) the body is rather more slender, 

 tapering more rapidly backward : (b) the frontal dentieulations 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 



