36 PROCEEDINGS OF THE NATIONAL MUSEUM. tol. 54. 



umbonal extension fonvard. The height is shghtly (one to two- 

 tenths) greater than one-half the length. 



The figured specimen (pi. 12, fig. 1) is the largest specimen seen. A 

 smaller specimen (M 1773), presenting more fully the specific char- 

 acteristics, has a length of 11 millimeters and is regarded as cotypical 

 with the former. 



Formation and locality. — Edmunds formation, northeastern part 

 of Crowe Neck (loc. 5.33.8 B), Trescott Township, Washington 

 County, Maine, gray shales near the top of the Edmunds formation. 



Remarks. —This species recalls Nucula coarctata Phillips=OMcwZ- 

 lella coarctata McCoy, from Fresh water. East, Pembrokeshire, Eng- 

 land; especially Phillip's figure 47, plate 26, from which our species 

 diffeis in its greater proportionate length. McCoy, in redefining the 

 species, mentions the proportion of height to length as 65/100 which 

 is approximately that of N. trescotti. 



Type-specimen.— Cat. No. 62875, U.S.N.M. 



NIJCULITES ROBUSTUS, new species. 



Plate 11, fig. 9; plate 12, figs. 4, 7, 10, 12, 14. 15. 



1839 cf. Cucullaea antiqua Sowerby, Murchison Sil. System, p. 602, pis. 3, 11 



and 12a. 

 1855 cf. Cucullella antiqua (McCoy) British Pal. Fossils, p. 284. 



A small, thick-sheUed species, much resembling CucuUaea antiqua 

 Sowerby, but having a more prominent overarching beak, stronger 

 clavicle and more transversely elongate form. 



Externally, the shell is transversely ovate, rather convex, beak 

 prominent overarching, posterior end produced, basal margin broadly 

 rounded, a shallow furrow below the inconspicuous umbonal ridge, 

 front margin rounded (pi. 11, fig. 9). 



Interior molds show prominent beak, arching over the hinge mar- 

 gins, terminating about \ length back from front margin. Clavicle 

 strong, straight, reaching beyond middle of shell; the anterior mus- 

 cular scar to within the space set off by the clavicle. Behind the 

 beak the interior of the shell is strengthened by a broad rib bounding 

 the posterior muscular scar on its front side. The cardinal edge is 

 strongly developed and has a continuous series of crenulate teeth 

 from near the front end of the hinge to a point beyond the front side 

 of the posterior muscular scar. 



In front the teeth incline inward toward the beak, and are slightly 

 longer than those behind the beak, which also incline inward toward 

 the beak. Those immediately under the beak are smaller than at 

 either end. 



Of 16 specimens measured, the average length is a little over 12 

 mm., the smallest 6^, the largest 18 mm. The average height 51/100, 

 the length, varying from 42 to 69 per cent. 



