CRUSTACEA. 263 



Remarks — The material present in the collection is entirely too fragmentary for 

 certain determination, but the form corresponds fairly closely with Acidaspis tubercalatus 

 Hall. It differs in the obsolescence of the anterior lobes, and the better definition of the 

 occipital segment. 



Horizon — Lower beds. 



Figured specimen No. 27548, Walker Museum. 



Family Proetidae 

 Genus Proteus Steininger 



Proetus conradi Hall 

 Plate 71, figure 2 



1900. Proetus conradi Clarke, N. Y. State Mus., Mem. vol. 3, No. 3, p. 25, pi. 2, figs. 



11-16. 

 1908. Proetus phocion Clarke, Mem. N. Y. State Mus., vol. 9, pt. 1, p. 135, pi. 9, figs. 

 14-16. 



Description — An incomplete cephalon is the only example representing this species. 

 The specimen possesses a subtriangular, strongly convex glabella with both extremities 

 well rounded, the anterior portion forming the apex of the triangle. Length slightly 

 greater than the width. The species is characterized by a flat marginal border which 

 is separated from the rest of the cephalon by a shallow groove. Cheeks gently convex, 

 borders flattened. 



Remarks — The strongly convex subtriangular glabella, together with the flattened 

 marginal border, are the characters used for the determination of this specimen. 



Horizon — Lower beds. 



Figured specimen No. 27550, Walker Museum. 



Proetus cf. pachydermatus Barrett 

 Plate 71, figure 3 



1903. Proetus pachydermatus Weller, Pal. N. J., vol. 3, p. 248, pi. 22, figs. 16-21. 

 1913. Proetus pachydermatus Maynard, Geol. Surv., Md. Low. Dev., p. 489, pi. 89. 

 fig/1. 



Description — This species is represented by several fragmentary, exfoliated cephala. 

 Cephalon small, semi-circular, with a broad, depressed convex, marginal border. Gla- 

 bella elongate oval, or subtriangular, moderately convex, anterior margin rounded, 

 posterior margin straight, the whole set off from the rest of the cephalon by a distinct 

 bordering furrow, or sulcus. The two anterior pairs of glabellar furrows are obsolete, 

 the third pair is pronounced, and curving to connect with the occipital furrow, thus 

 forming two distinct lobes at the base of the glabella. 



Cheeks poorly preserved, free cheeks entirely lacking. Facial sutures and other 

 characteristics not shown in the incomplete specimens. 



Remarks — The form resembles Proetus pachydermatus Maynard from the Helder- 

 berg of Maryland, but lacks the small basal lobes situated posterior to the glabella 

 basal lobes. 



Horizon — Lower beds. 



Figured specimen No. 27549, Walker Museum. 



Proetus protubcrans Hall 



Plate 71, figures 4-7 



1859. Proetus protuberans Hall, Nat. Hist. N. Y. Pal., vol. 3, p. 351, pi. 73, figs. 5-8, 

 1861. 



