316 



PAL-EONTOLOGY OF NEW-YORK. 



along the centre, abruptly bent downwards at their extremities, and terminating in sharp 

 points ; caudal axis with eight articulations ; lateral lobes with five broad shallow grooves 

 extending to the margin ; extremities of the articulations of the thorax, and margin of caudal 

 shield, striated like the margin of the cephalic shield. 



This rare species is very peculiar, and remarkably distinct from any species of the genus 

 known to me, and from the described species which have fallen under my observation. It pos- 

 sesses the characteristics of the genus, as illustrated in the best specimens figured. In the 



character of the caudal extremity, it approaches more nearly to Proetus sp. (Salter, pi. 



vi, fig. 4, Memoirs Geol. Survey of Great Britain, Vol. ii, part 1), but it is probably a distinct 

 species. 



In one of the specimens examined, the termination of the facial sutures in front is distinctly 

 visible ; and the space between them in the margin is equal to one-third of the margin of the 

 shield, exclusive of the spines at the posterior angles. 



Fig. 15. A specimen, natural size. 



Fig. 15 a. The cheek, separated at the facial suture. 



Position and locality. In the shale bf the Niagara group at Lockport. 



676. 2. PROETUS? STOKESII. 



Pl. LXVII. Figs. 13 and 14. 



Reference, jlsaphus stokesii. Murchison, Sil. System, 1839, pag. 625, pl. 14, fig. 6. 

 " Proetus {Asaphus') stokesii. Loven, 1845, pag. 50, T. 1, fig. 3. 



" .^onia stokesii. Burmeister, Organization of Trilobites : R-iY, Soc. translation, 



p. 100. 

 Compare Forhesia latifrons, M'Coy, Sil. Fossils of Ireland, pag. 49, pl. 4, fig. 11. 



" Proetus latifrons, Salter, Memoirs Geol. Survey of Great Britain, Vol. ii, part 1, 

 pag. 337, pl. vi, fig. 1. 



Oval, convex ; width about five-sevenths of the length ; head a little more than three-fifths 

 the length of the body ; axis rather prominent and narrow ; cephalic shield crescent-form, with 

 long posterior spines ; margin elevated, and the space between it and the cheeks and glabella 

 depressed in a broad shallow groove ; glabella oval, smooth, very prominent in front ; cheeks 

 convex ; eyes small, prominent, close to the glabella ; spines rather thick and strong, reaching 

 to the eighth segment of the body ; axis of the body (in a specimen not compressed) narrow 

 and prominent ; caudal shield with the lateral lobes marked by six or seven ribs, which are 

 divided half way from the axis, and terminate in a thickened border. Surface granulate. 



Two individuals of this species only have been seen j one of them is in soft shale, and some- 

 what flattened, the eyes obliterated, the glabella and part of the axis of the body and tail worn 

 or broken, while the margin of the cephalic shield with the spines is well preserved. The 

 other specimen is partially folded, and the caudal axis not visible. In this specimen the pro- 

 minent glabella and one cheek are well preserved, as well as the spines of the cephalic shield 

 and articulations of the thorax. 



