Marylaxd Geological Survey 499 



Genus DALMANITES Emmrich 



Dalmanites aspinosus Weller 

 Plate XCI, Fig. IG 



Dalmanites aspinosa Weller, 1903, Pal. N. J., vol. iii, p. 252, pi. xxii, fig. 15. 



Description. — " Known only from the pygidinm which is longitudinally 

 semielliptical in outline, obtusely pointed posteriorly. Axis regularly 

 tapering and rounded posteriorly ; in the type specimen reaching to within 

 4.5 mm. of the posterior margin, which makes it about six-sevenths of tlie 

 entire length of the pygidium; marked by about 16 annulations, which 

 gradually decrease in size posteriorly until they become entirely obsolete. 

 The pleura are rather strongly convex to the margin, with no flattened or 

 concave border; marked by ten prominent, narrow grooved ribs, which 

 extend to the margin of the pygidium and are separated by broad, concave 

 furrows. The dimensions of the type specimen are : Length 32 mm. ; 

 width 40 mm. ; convexity 9 mm." Weller, 1903. 



• The individuals in Maryland are smaller than those from New Jersey. 

 However, the characteristics, i. e., the absence of any spinous extension 

 from the posterior extremity, the absence of any flattened or concave 

 marginal border and the sharp pleural angular ribs which are present, 

 distinguish this species conspicuously from other members of the genus. 



Occurrence. — Helderberg Formation, Keyser Member. Devil's 

 Backbone, Cash Valley. 



Collection. — U. S. National Museum. 



[Maynard.] 



Dalmanites keyserensis n. 

 Plate XCI, Figs. 8, 9 



Description. — Head semielliptical, posterior edge semicircular. Gla- 

 bella convex, length from posterior furrow to anterior margin 10/11 width 

 of the frontal lobe. Frontal lobe rhomboidal, length 3/5 its width. Pos- 

 terior lobes narrower, separated by well-defined transverse furrows, the 

 two anterior furrows appearing as narrow pit-like depressions on either 

 side of center, becoming faint towards sides; posterior furrow extending 



