500 Systematic Paleontology 



entirely across axis. Eyes very prominent, elevated, exterior sides set 

 with numerous facets which are absent next glabella from which they are 

 separated by a deep sulcus. Margin elevated and angular, bounded by a 

 depression which separates it from glabella and cheeks. Genal angles 

 broad, greatly extended, their length equal to length of glabella. Thorax 

 not observed. Surface of glabella finely papillose. Part of a pygidium 

 was associated with the head and probably belongs to the same species. 

 It is semielliptical, its axis tapering gradually, its anterior diameter 1/8 

 width of pygidium. Pleura broad, extending to margin. Posterior 

 extremity unknown. A single specimen is known. 



Length of head exclusive of genal angles 16 mm. Length of angles 15 

 mm. ; width of head 30 mm. ; width of frontal lobe of glabella 12 mm. 



The head of this species resembles that of D. pleuroptyx, but the frontal 

 lobe is more sharply limited by furrows; the posterior lobes are much 

 narrower in proportion to width of anterior lobe, and their width does not 

 diminish so rapidly posteriorly; the transverse furrows are more pit-like. 

 The genal angles are broader and proportionately longer. This may be 

 D. aspinosa of Weller, but the head of that species has never been described, 

 while the pygidium of this form is known only by a fragment which is too 

 imperfect to permit confident determination, although it resembles the 

 pygidium of D. aspinosa. It seems best to describe it as new pending the 

 discovery of additional material. It occurs in the Chonetes jerseijensis 

 zone. 



Occurrence. — Helderberg Formation, Keyser Member. Tonoloway 

 193.1 feet above base of formation. 



Collection. — Maryland Geological Survey. 



[Swartz.] 



Dalmanites multiannulatus n. sp. 

 Plate XCI, Figs. 12-15 ; Plate XCII; Plate XCIII, Fig. 1 

 Description. — Complete cephalon not seen. Fragments show the follow- 

 ing characters : Convex, depressed ; a broad concave border extends from 

 one genal angle to the other ; within and concentric with this is a narrower 

 arched ridge; with and concentric with this ridge is a second concave 



