112 BULLETIN OF THE 



no radiating lines. Interior smooth and polished ; the process for the ligament 

 is small, rounded, triangular, and projects downward directly from the tip of 

 the beak, instead of being obliquely continued along the hinge margin, as in 

 the above and most other species ; a ridge runs along just below the anterior 

 cardinal margin, as if tbe said margin had been pressed upward and outward 

 from within ; the space between the ridge and the margin is a little excavated. 

 Lon. 15.0 ; alt. 9.5 ; maj. diam. 8.0 ; rostrum, (about) 5.0 mm. From the 

 beak to the anterior margin is seven fifteenths, and from the tip of the rostrum 

 to the line of the beak is eight fifteenths of the whole length. 



Barbados, 100 fms. (young) ; Station 44, 539 fms. ; Yucatan Strait, 640 fms. 



I am glad to be able to dedicate this species to my friend Dr. Jeffreys, who 

 has added a number of new species to this genus in his account of the mollusks 

 of the Valorous expedition. 



Nesera claviculata n. s. 



Shell white, thin, translucent, polished, shining, covered with (about fourteen 

 to the millimeter) numerous fine, regular, rounded, concentric undulations or 

 narrow waves, fainter and more distant on the umbones ; shape not unlike 

 that of Portlandia arctica as figured by G. O. Sars (op. cit., tab. 4, fig. 7 a), 

 but shorter, more inflated, with the beaks more prominent and more directed 

 forward, the posterior cardinal margin excavated instead of produced, and the 

 rostrum itself more pointed and without the strong rib which characterizes 

 this part in the Nuculid. Interior marginated more or less distinctly all 

 round ; spoon for the ligament small, posteriorly directed ; from behind it, 

 two thirds of the way toward the tip of the rostrum and broadening as it pro- 

 ceeds backward, extends a laminar buttress or "clavicle," lying within the 

 marginal ridge and margin ; beaks almost exactly midway between the two 

 extremities of the shell ; radiating sculpture none. Lon. 12.0 ; alt. 8.5 ; 

 diam. (approx.) 6.5 mm. 



Station 44, 539 fms. (one right valve). A fragment of which the sculpture 

 resembled that of this species was obtained by Sigsbee off Havana, in 450 fms. 



This species is remarkable foi its abbreviated form, total absence of radiating 

 sculpture, and singular clavicle. I have seen nothing of the latter kind in any 

 species I have examined except this one. 



Nesera sp. indet. 



A fragment from off Cape San Antonio in 1,002 fms., somewhat resembling 

 tin' last species in shape, but not in sculpture, indicates a rather large-sized 

 form. 



Nesera limatula n. 8. 



Shell of moderate size, thin, white, elongated, with the rostrum hardly dif- 

 iated from the real of the valve ; sculpture consisting of sharp-edged con- 

 Oct. 31, 1881. 



