MUSEUM OF COMPARATIVE ZOOLOGY. 305 



Myonera laticella, n. s. 



Shell large, thin, inflated, rather short, white with a pale brown epidermis; 

 beaks full, prominent, their apices touching over the cartilage; right valve a 

 little the larger; sculpture of concentric, elevated, thin, but not sharp-edged 

 lamellae, more distant on the beaks, higher and more crowded toward the basal 

 margin, failing at the anterior boundary of the rostrum where they are repre- 

 sented by the fine incremental striae, if at all; radiating sculpture consisting 

 of somewhat irregular distant sharp elevated lines, which are most abundant 

 between the middle of the shell and the rostrum; these rise up under but do 

 not cut through the concentric lamellae, which by them are thrown into waves, 

 like loose cloth lying over several cords stretched taut, which waves grow 

 obsolete toward the base; there are also extremely fine radiating striations on 

 the smooth rostral areas, which are bounded by an imaginary line extending 

 obliquely from the beaks to the lower extreme of the rostrum ; these striations 

 bear elevated lines of epidermis ; there is a very narrow depressed area along 

 the cardinal margin behind the beaks; the margin of the right valve fits over 

 the posterior part of the rostral margin of the left valve; the rostrum itself is 

 short, slightly recurved and obliquely rounded oflF from below, and in a less 

 degree from above, to form a gaping rounded tip; the hinge-line is simple, with 

 a rather large posteriorly directed fossette for the cartilage in each valve, and 

 without buttresses ; the cartilage is reddish brown, and carries a subrectan- 

 gular ossicle; approximate length of shell (broken) 20.0; of young shell (taken 

 from lines of growth) Ion. 8.0, alt. 5.0, diam. (about) 5.0 mm. From the tip 

 of the rostrum to the beaks at the cartilage measures in the adult 13.5 mm., 

 and the diameter when perfect must have been at least as much. 



Habitat. Near Curacoa, at U. S. Fish Commission Station 2126, in 1701 

 fms., yellow mud, bottom temperature 39°.3 F. One living but broken speci- 

 men of which the base and anterior end were gone. 



This very elegantly sculptured species is so difiFerent from any of those 

 described that I felt justified in characterizing it from the imperfect specimen. 

 Apart from its sculpture it somewhat resembles M. undata Verrill in general 

 form, though the rostrum in that species is shorter and the fossette propor- 

 tionally smaller. 



Family ANATINID^. 



Gencs PERIPLOMA Schumacher. 



In the region covered by the investigations of the " Blake " several species of 

 this genus are indigenous. P. incequivalvi^, the type, is often found on sandy 

 beaches, but usually only the convex valve, destitute of its ossicle. The most 

 common species on our Southern coast is the P. anguli/era Phil., described 



VOL. XII. — NO. 6. 20 



