NO. 1908. NEW SILURIAN MOLLUSC A FROM MAINE— WILLI A MX. 389 



angles to this line and about one-quarter diameter in front of 'pos- 

 terior margin 16 mm.; estimated depth of shell at middle not over 

 5 mm. The type-specimen is a left valve. 



Locality. — East side of Seward Neck. 



Eolotype.—C&t. No. 58439, U.S.N.M. 



EURYMYELLA RECTA, new species. 



Plate 49, fig. 15. 



Shell triangular, narrow, erect, higher than long; beak small, 

 depressed, nearly central; hinge line short, straight; umbonal ridge 

 low, convex, nearly central and nearly vertical to the hinge line; 

 umbonal ridge trending about 10° posteriorly from the vertical. 



Dimensions. — Greatest length at about 3 mm. below the hinge 

 line, 16 mm.; height from beak to front 21 mm. 



This species resembles E. shaleri, var. hreva, but differs by its 

 depressed, flattened beak, indistinct umbonal ridge, more central 

 position of the beak, and larger size. It bears closer genetic relation- 

 ship to E. angularis and E. plana, with which it is associated in the 

 same beds. 



Locality. — East side of Seward Neck. 



Eolotype.—C&t. No. 58440, U.S.N.M. 



EURYMYELLA CONVEXA, new species. 

 Plate 50, fig. 10. 



Shell ovoid, oblique, convex; beak strong but not much produced 

 beyond the hinge line, and situated about one-tliird way posterior to 

 the front end of the liinge. Hinge line straight, shorter than the 

 greatest length of shell, at posterior end sloping down gradually into 

 the posterior margin; anterior ear narrow. I^mbonal ridge broad, 

 convex, liighest near middle of shell, its axis forming an angle of 

 about 45° with the posterior liinge line. The surface behind the 

 umbonal ridge falls off rapidly to a broad, depressed area, gradually 

 flattening to the tip of the broadly rounded cardino-posterior angle. 

 Tiie anterior ear is small, and from near its tip to the base of the 

 umbonal ridge the margin trends in a broad, regular, convex curve 

 to the ventral margin. 



The type-specimen is a mold of the interior of a left valve, and 

 shows the well-defined pit of the anterior muscular scar situate close 

 in front of the ear and upon the hinge line. Tliree Uttle scars are 

 evident on the front side of the umbonal cavity, and a fourth just 

 above and behind the muscular scar. An indistinct trace of an 

 obUque tooth is evident under the beak, and near the posterior ex- 

 tremity of the liinge a short linear tooth about 3 mm. long is c^^dent. 

 The surface is marked by couceiiLric lines and a few irregular con- 

 centric furrows. 



