64:0 Systematic Paleoxtology — IJprER Devoxiax 



This species is distinguished from all others in the fauna by its faint, 

 radiating stride, a feature observed also on the specimens from Xew York. 

 It is confined so far as observed to a single horizon near the base of the 

 Parkhead fauna. 



Occurrence. — Jexkings Formation, Paukhead Member. Road 1 

 mile north of Eocky Eun ; Williams Eoad, east of Cumberland, 1393 ; 

 Williams Eoad, on Polisli Mountain, 1163; National Eoad, on Polish 

 Mountain, 1196; 21/2 miles above mouth of Sideling Hill Creek; National 

 Eoad west of Tonolovi^ay Eidge. 



Collection.' — Maryland Geological Survey. 



Leptodesma lichas Hall 

 Plate LXIII, Figs. 18, 19 



Leptodesma lichas Hall, 1884, Pal. of N. Y., vol. v, pt. i, p. 232, pi. xxi, figs. 

 35-39; pi. xci, figs. 19, 20. 



Description. — Shell having proportions similar to those of L. longi- 

 spinum but the umbonal ridge is more conspicuously developed and nearer 

 the hinge, making a shorter cardinal slope and a broader antero-ventral 

 slope, the latter barely depressed by the byssal sinus. The umbo is 

 prominent and overarches on the hinge-line. No extended spine on the 

 posterior extremity. 



These shells occur occasionally in association with L. longispinmn and 

 though smaller than the usual New York examples retain throughout the 

 expression of the species. 



Length 30 mm.; height 20 mm. 



Occurrence. — Jennings Formation, Chemung ]\Ie]mber. Deer Park; 

 National Eoad west of Frostburg; Oakland-Eedhouse Eoad; Town Creek, 

 3584 common, 3760, 3963, 4631. 



Collectionj — ^Maryland Geological Survey. 



Leptodesma elongatum n. sp. 



Plate LXIII, Fig. 20 



Description. — Shell large, elongate subrhomboidal; body spatulate, 

 very oblique, length of hinge-line less than one-half length of body. An- 



