MUSEUM OF COMPARATIVE ZOOLOGY. 241 
Report (1. c., p. 121), I reported the pectunculoides (with which Prof. Verrill 
had seemed disposed to unite glacialis) from the Gulf, but expressly objected 
to its identification with glacialis, which I do not know from that region, 
Arca polycyma Dat. 
Arca polycyma Dall, Bull. M. C. Z., IX. p. 122. 
Plate VIII. Figs. 3, 3 a. 
Habitat. Barbados, 100 fms., three valves ; a single valve at Station 262, 
near Grenada, in 92 fms. 
Only one more valve of this interesting little species has turned up since the 
original specimens were described. 
Arca glomerula Dat. 
Arca glomerula Dall, Bull. M. C. Z., IX. p. 121, 1881. 
Arca (Scapharca ?) inequisculpta E. A. Smith, Chall. Rep. Lam., p. 267, pl. xvii. figs. 
8a-8c, 1885. 
Plate VIII., Figs. 9, 9a. 
Habitat. Barbados, 100 fms.; Bache, April 22, 1872, Lat. 21° 14’, 100 fms.; 
Station 20, 220 fms.; Station 19, 310 fms.; Sigsbee, off Havana, 450-480 fms. ; 
Station 100, off Havana, in 400 fms.; Stations 206 and 211, in 170 and 357 fms. 
off Martinique, bottom temperature 49°.0 F. to 62°.0 F. The Challenger 
specimens were obtained from off Culebra Island, West Indies, at Station 24, in 
390 fms., pteropod ooze. 
The specimens described by me in 1881 were separated valves, and the 
differences of sculpture, noted at the time, were set down to individual varia- 
tion. Mr. Smith has, however, shown that the difference is between the two 
valves of the same specimen. There is generally a single more prominent rib 
on the posterior slope of the right valve, but nothing of the kind in the left 
valve. 
Arca auriculata Lamarck. 
Arca auriculata Lam., An. s. Vert., VI. p. 48, 1819. 
Habitat. Station 142, in 27 fms., Flannegan’s Passage; and at Station 12, 
off Havana, in 36 fms. 
A single living specimen of this species was obtained in each case. The 
foot is of good size and deeply grooved, the byssus small. A sort of bridle of 
tissue from below the mouth passes under the anterior adductors and thence 
to the interior of the umbones, where it is strongly attached and then sweeps 
VOL. XII. — NO. 6. 16 
