108 BULLETIN OF THP: 



tant, slightly elevated threadlike lines ; shell smooth, except that a faint 

 impression of radiating lines is left by the epidermis ; beaks inflated ; basal 

 margin arcuated ; anterior margin rounded ; posterior margin slightly pro- 

 duced, pinched, and truncated : ossicle extremely minute (or none ?). Lon. 

 IG.O; alt. IG.O ; max. diam. 12.0 mm. 



Lat. 21° 33' N., Lon. 84° 23' W., 1920 fms. 



This has a curious superficial resemblance to the next species, except that it 

 wants the granules. 



POROMYA Forbes. 



Poromya Forbes, Kep. ^gean Sea, p. 143, 1844. (P. anatinoides.) 



This genus is clearly distinct from Thetis Sowerby (T. mdnor), which has an 

 internal laminar buttress in the hollow of the beaks, although the two have 

 been very generally united by authors, following the lead of H. and A. Adams. 

 I do not feel sure that Eucharis Eecluz is an exact synonym, though the name 

 is several times preoccupied and must be given up. Emhla Loven appears 

 to be an exact synonym of Poromya. The pallial line is sliglitly sinu- 

 ated in the latter, and there is a cardinal tooth only in the right valve, the 

 ligament is almost entirely internal, and in the specimens I have seen there 

 has been no ossicle. The group is closely related to Nccera and Verticordia by 

 the shell characters. 



Poromya granulata Nyst and West. 



Thetis granulata Nyst and Westendorp, H. and A. Adams, Gen. Ree. Moll., II. 367, 

 PI. XCVII. figs. 2 a, 2 b. 



Sand Key, 15 fms. ; Station 36, 84 fms. ; Station 32, 95 fms. (valve 19.5 high 

 by 21.0 mm. in length) ; Station 45, 101 fms. (valve 16.0 high by 22.0 mm. 

 long); Station 9, 111 fms.; Station 5, 229 fms. Barbados, 100 fms.; off 

 Sombrero, in 45 fms. ; these two specimens belonging to the var. triangularis. 



Having no specimens of the genuine P. granulata to compare, the deter- 

 mination is not absolute, especially as the figures of that sjjecies given by 

 Adams and Jeffreys differ considerably among themselves, but the variation in 

 form is considerable, as the above measurements show, and I feel little doubt 

 that this is the true P. granulata. A form belonging to this genus has been 

 insufficiently descri])ed by Jeffreys (under the name of rotundata) from one 

 broken valve obtained in Lat. 56° 11' N. and Lon. 37° 41' W., in 1450 ihthoms, 

 on the Valorous cruise. Professor Verrill has amplified this description a little; 

 l)ut in consideration of the great variation in the form of the shell, number and 

 distribution of the granules and their coarseness, visible in the specimens 

 before me, I see no reason for considering the characters mentioned by Jeffreys 

 as of importance enough to deserve a separate name. I note a very triangular 

 variety from two localities, probably only an extreme variation of the type. 



