296 BULLETIN OF THE 



Cuspidaria(?) axcuata DaU. 



Ne(Bra arcuata Dall, Bull M. C. Z., IX. p. 113, 1881. 



Flate III. Fies. 3, 4. 



Habitat. Yucatan Strait, 640 fms. 



As only a single left valve of this species was obtained, it has been imprac- 

 ticable to determine to what section it belongs, but the general aspect is that 

 of Cuspidaria, or a Balonympha without a clavicle. 



Subgenus CARDIOMYA A. Adams. 



Similar to the preceding, but with radiating sculpture and the fossette more 

 vertical and prominent. Type Necera Gouldiana Hinds. 



C. multicostata V. & S., C. perrostrata Dall, and C. ornatissima D'Orbigny 

 (-\- costata Bush) belong here, as do N. pectinata Cpr. (1865, + var. behring- 

 ensis Leche, 1883, from types), and C. califomica Dall.* (See Plate III. 

 fig. 6.) 



Cuspidaria (Cardiomya) perrostrata Dall. 



Necera (ornatissima D'Orb. var.?) perrostrata Dall, Bull. M. C. Z., IX. p. 110, 1881. 

 Necera perrostrata Verrill, Trans. Conn. Acad., V. p. 661, 1882. 



Plate II. Figs. 3 a, 3 b. 



Habitat. Station 43, 339 fms., off Tortugas, bottom temperature 45°.0 F.; 

 Station 264, in 416 fms., gray ooze, near Grenada, bottom temperature 42°.5 F. 



Desiring to be as cautious as possible in describing new forms based on very 

 little material, I referred to this and D'Orbigny's C. ornatissima as possibly 

 identical, in my preliminary descriptions. That there is a good deal of varia- 

 tion in this group is clear, when plenty of material is accessible; but I am the 

 more confirmed in the belief that this one is specificallj' distinct by Professor 

 Verrill's opinion, and by the fact that the Fish Commission has obtained off 

 the Carolinas, and Miss Bush has described (as Necera costata), a form which 

 seems to be identical with D'Orbigny's, and is certainly distinct from the 



• Cuspidaria (Cardiowyn) cnlifornica Dall. Shell differing from C. pectinata by its 

 smaller size and proportionally greater length ; larger number of ribs (16-20, wliiJe 

 pectinata averages 12-14) ; its straighter, longer rostrum with but two strong radi- 

 ating lirae extending to the lower extreme {pectinata has none, or only several fine 

 ones near the body of the valve) ; its less inflated shape and paler more delicate 

 epidermis. Lon. of sliell 7.0; of rostrum 2.5; alt. of shell 3.6; diam. 2.75 mm. 

 Color yellowish white ; ossicle as usual; buttress present in the right valve. 



Habitat. Catalina Island, California, dredged in 16 fms., mud ; Dall, and pre- 

 viously Cooper, who confounded it, following Carpenter, with pectinata. 



