390 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.42. 



The impression of tliis shell indicates a much stiffer and therefore 

 tliicker shell than in most of the representatives of the genus. From 

 its association with the other species and its agreement in the ex- 

 terior elements of form with the smaller species, I conclude that the 

 development of evident liinge teeth is incident to the fuller develop- 

 ment of the shell, and that it may be, generically, associated with 

 the typical Eurymyellas with wliich it agrees in tlie entire absence 

 of a mesial sulcus wliich is characteristic of the ordinar}^ forms of 

 Modiolojysis and ModiomorpTia, to which genera these Eurymyellas 

 have been frequently referred. 



Dimensions. — The straight part of the hinge, length 15 nam.; 

 length from front to back at 5 mm. below liinge line, 25 mm. ; height 

 at posterior end, 20 mm. ; greatest diameter fi'om tip of anterior ear 

 to postero-ventral angle, 30 mm. 



The type-specimen of tliis species was collected by N. S. Shaler 

 and the specimen was identified as " Modiomorplia sp. subulata" by 

 Shaler and later listed by H. S. Williams as Modiomorplia sp. subulata 

 var. in United States Geological Survey Professional Paper, No. 35, 

 page 24. The entire absence of the sulcus anterior to the umbonal 

 slope and the discovery that the associated forms, generally of 

 smaller size, are, with scarcely an exception, without tliis sulcus and 

 present the general outward features of McCoy's Anodontopsis 

 augustifrons, led to the founding of the new genus Eurymyella for 

 the reception of tliis and associated species. 



Locality. — Salt Works, Eastport. 



Eolotype.—Ca,t. No. 58448, U.S.N.M. 



EURYMYELLA DENBOWENSIS, new spedes. 

 Plate 50, figs. 11 and 14. 



Shell subtriangular, obliquely elongate in the direction of the 

 umbonal ridge; hinge line straight, shorter than length of the shell. 

 Beak low, scarcely protruding beyond the hinge line, and situated 

 near the front end. Umbonal ridge subangular, low, running from 

 beak to postero-basal angle; lateral slopes subequal, flattened but 

 shghtly convex, no mesial sinus in front of umbonal ridge. 



Surface marked by concentric lines of irregular size. Anterior 

 muscular scar, strongly impressed near end and close up to the 

 liinge; two or three small pits between it and the beak cavity. One 

 or two small oblique teeth under the beak; linear thickening, but 

 no distinct posterior lateral teeth are evident. The inner edge of 

 the hinge-area somewhat strengthened at its posterior end. 



Dimensions.— Gveatest diameter from tip of front to extremity of 

 the umbonal ridge of the type-specimen, 28 mm.; greatest diameter 

 near center of shell at right angles to the umbonal ridge, 14 mm.; 



