56 



Measurements (in millimètres) 



Length 5.5 4.5 4.4 3.8 



Height. ... 7 • • 5 4-2 3-8 3-5 



Thickness of single valve 2 1.6 1.6 1.4 



The first three valves are the left valves and the fourth a right valve. 

 Habitat : — The 4 stray valves, which are quite fresh and not weathered, were dredged 

 at St. 211 (5°4o'.7S., i20°45.5E.) from a depth of 1158 mètres. 



Remarks: — A. {B.) sibogai is allied to A. {B.) anaclima MelvilP), but is distinguished 

 by the larger and différent shaped shell : the sculpture is also very différent. 



3. Arca [Bathyarca] sp. (Plate II, fig. 4). 



A dead, somewhat worn, single right valve dredged from a coarse sandy bottom at St. 159 

 (o°59.i S., 129° 48^.8 E. 411 mètres) belongs undoubtedly to an undescribed species of the subgenus 

 Batkyarca, but in view of there being only one valve available I refrain from describing the 

 species. The measurements of the valve are: — length 12.5 mm., height 12 mm., thickness of 

 single valve 4.8 mm. The sculpture consists of prominent radial ridges which are traversed by 

 low concentric ridges giving rise to a reticulate sculpture over some parts. A photograph of 

 the shell is published on pi. II (fig. 4). 



4. Arca {Bathyarca) sp. (Plate II, figs. 5, 6). 



I am unable to refer to any known species two stray, dead valves, both left, dredged 

 from a depth of 462 mètres at St. 212 (5°54'.5S., 1 20° i9'.2 E.), but in view of the shells 

 beingf incomplète, I refrain from giving them a name or describing the species. I however, publish 

 photographs of the two shells on pi. II (figs. 5, 6). Thèse valves represent a species which 

 probably is the largest of the Bathyarcas so far known. The sculpture consists of a large number 

 of very regular, well marked, but minute concentric threads, a few very shallow radial threads 

 are also to be distinguished on the anterior and posterior thirds of the valves; thèse are more 

 prominent on the younger of the two spécimens. 



Measurements (in millimètres) 



Length 10 22 



Height 9 18.2 



Thickness of single valve 3.5 8.3 



Genus Cucullaea Lamarck. 



1801. Cucullaea Lamarck, Syst. Anim. sans Vertèb., p. 116. 



1857. Cucullaea Adams, H. & A., Gen. Rec. Moll., II, p. 539. 



1898. Cucullaea Dali, Trans. Wagner Free Inst. Sci. Philadelphia, III, p. 603. 



1907. Cucullaea Lamy, Journ. Conchyliol., LV, p. 11. 



This genus was placed by Dall in the family Parallelodontidae of the superfamily 

 Arcacea, but I see no reason for not including it in the family Arcidae. 



l) Melvill, J. C. — Proc. Zool. Soc. London (1906), p. 794, pi. LIV, figs. 6, 6a (1907). 



