370 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
below the opisthogyrate beaks; no lunule; dorsal slopes and base arcuate, ends 
rounded ; interior pearly with entire margins; hinge with 15-17 anterior, and 7 
posterior teeth, the chondrophore narrow, small, obliquely anteriorly directed. 
Length of shell, 15; of posterior end, 5; alt. 10.5; max. diam. 7.5 mm. 
U. S. “Albatross,” station 2780, Magellan Straits, m 369 fathoms, mud, 
bottom temperature 47° F. U.S. N. Mus. 96,243. 
Named in honor of Magellan’s historiographer. A particularly rude and turgid 
species; all of the specimens were thickly encrusted with a ferruginous coating. 
Nucula agujana Datzt, n. sp. 
Plate 10, figures 6, 7. 
Shell small, inequilateral, plump, polished, nearly black with paler olivaceous 
umbones, subtriangular in outline; umbones high, full, opisthocoelous; posterior 
dorsal slope flattened, but with no areal limitation, short; anterior slope longer, 
arcuate, without a defined lunule; anterior end rounded, posterior subangular ; 
basal margin evenly arcuate: surface smooth at the umbones, over the rest of the 
disk with irregular, rather course concentric incremental lines ; interior pearly, 
with deep muscular impressions, and smooth valve margins; hinge with nine 
posterior and fifteen anterior teeth, separated by a narrow, oblique chondrophore. 
Lon. of shell, 11, of beaks before the posterior end, 3; alt. 8; diam. 5.75 mm. 
U. 8. 8. “ Albatross,” station 4654, twenty-four miles N. 68° W. from Aguja 
Point, Peru, in 1036 fathoms, mud, bottom temperature 37°.3 F. U.S. N. 
Mus. 110,571. 
Nucula exigua Sowersy. 
Nucula exiqgua Sowerby, P. Z. S. London, 1832, p. 198; Conch. Tll., figs. 24, 24* 
(bad); Hanley, Thes. Conch. Nuculidae, p. 50, fig. 186 (mediora). 
Bay of Panama, Cuming; U.S. 8. “ Albatross,” station 3418, off Acapulco, 
Mexico, in 660 fathoms, sand, temperature 39°; station 2807, near the Gala- 
pagos Islands, in 812 fathoms, ooze, temperature 38°.4, station 4654, off Aguja 
Point, Peru, in 1036 fathoms, mud, temperature 37°.3; stations 2783, and 2784, 
on the west coast of Patagonia, in 122 and 194 fathoms, mud, temperatures 48° 
and 51°.9 F. 
Hanley’s figure, of all I have seen, is the only tolerably good one. All the 
extant figures are made from immature specimens; the fully adult specimens are 
less oblong, more triangular, and more inflated. Nucula pisum Sowerby and 
NV. semtornata Orbigny are perhaps synonymous. 
Nucula chrysocoma Datt, n. sp. 
Plate 18, figures 3, 4. 
Shell small, plump, solid,.subtriangular, brilliantly polished and of a light 
yellowish olive color; beaks moderately prominent, the prodissoconch showing 
