RAYMOND AND BARTON: AMERICAN SPECIES OF CERAURUS. 541 



of the glabella and the direction of the posterior glabellar furrows 

 exclude this species from Cheirurus. 



Formation and Locality. — This species is very rare in the 

 English Head formation, (Richmondian), at English Head, Anticosti. 



Species incorrectly referred to Ceraurus. 



Encrinurus rarus (Walcott). 

 Plate 2, fig. 3. 



Ceraurus rarus Walcott, 31st rept. N. Y. state mus. nat. hist., 1877, 

 p. 15 (advance sheets); 31st rept. N. Y. state mus. nat. hist., 

 1879, p. 68. 



Through the kindness of Professor Weller we have been able to see 

 the type of this species. The specimen now belongs to the Walker 

 Museum at the University of Chicago, and bears the number 12,322. 

 It retains only the glabella and a part of one fixed cheek, and is 3 mm. 

 long. The glabella is very narrow in front of the neck-ring, but 

 expands rapidly toward the front. The glabella differs from that of 

 any known species of Ceraurus in that it contracts in front of the neck- 

 ring, so that the sides are not straight, but concave toward the fixed 

 cheeks. The posterior pair of lobes are also extremely small, and not 

 isolated, the last furrows being straight. All of the glabellar furrows 

 are straight, or turn a little forward at their inner ends, none of them 

 turning back as in nearly all species of Ceraurus. These features 

 excite suspicion as the generic identification of the specimen. 



The specimen was collected at Beloit, Wisconsin, and Dr. Clarke 

 has described, from that same locality, a species which he called 

 Encrinurus vannulus. Although the figure given by Clarke l is poor, 

 his description fits the present specimen exactly. He says, in part : — 

 " Lateral furrows obscure, but still more distinctly developed than is 

 usual in this genus. The first pair lies a short distance from the an- 

 terior extremities of the dorsal furrows, is short, and directed somewhat 

 anteriorly, the second and third furrows are but slightly longer, some- 

 what more transverse .... Occipital ring broader than the lateral slopes, 

 and expanding considerably beyond the base of the glabella." 



As there can be no doubt that Dr. Clarke's specimens belong to the 

 genus Encrinurus, and as Ceraurus rarus is from the same locality, 



1 Paleontology Minnesota, 1897, 3, pt. 2, p. 739, fig. 56. 



