358 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
The specimens from the stations above, to which is prefixed an asterisk, — in 
addition to being thinner-shelled, with a slightly more even curvature, circular aper- 
ture, with the longitudinal sculpture retaining its sharpness to the end, instead of 
flattening out as in typical megathyris, — have also at the anal end on the dorsal 
side a notch which varies from 1.0 mm. to 7.0 mm. in length, while in the 
best preserved typical megathyris observed in the young stages, the anal aper- 
ture is always entire. For this variety, which seems to grade into the type, the 
varietal name of panamense is proposed, though it may eventually prove to be a 
distinct species. 
Dentalium peruvianum DALL, n. sp. 
Shell white, straight, except for a slight curve near the anal end which is at its 
maximum about 20 mm. in front of the anal end; surface with an extremely thin, 
yellowish periostracum, finely longitudinally striated, with wider slightly rounded 
interspaces varying more or less in width ; these interspaces rise into thread-like 
form near the anal end, where they alternate in size, but are never very strong; 
there are about twenty-six of them just in front of the slit; in advance of this 
point the intercalaries chiefly begin; the anal end is rounded, about 1.75 mm. 
in diameter, with a wide slit on the convexly arcuate or dorsal side, the slit at its 
beginning is 1.7 mm. wide, and has a length of 5.0 mm. The oral aperture is 
nearly circular, measuring 19.0 mm. wide and 11.25 mm. dorso-ventrally ; the 
margin is very sharp and thin; the type specimen measures 90.0 mm. in length, 
of which two-thirds is nearly straight, the maximum deviation of the ventral sur- 
face from a chord connecting the two extremities is 9.5 mm., about 20.0 mm. in 
front of the anal end. 
U. S. S. “Albatross,” station 4656, in 2222 fathoms, mud, off the Peruvian 
coast in S. Latitude 6° 55 ‘and W. Longitude 83? 34’; bottom temperature 35.2 F. 
U.S. N. Mus. 110,667. Also at station 4649, in S. Latitude 5? 17’ and W. Longi- 
tude 85° 20’, in 9935 fathoms, mud, temperature 35°.4, a fragment of the same 
species. 
The type specimen had served as a pedestal for a large deep-water Actinia. 
The species is straighter, more slender, and less tapering, and with a much 
feebler sculpture than D. panamense, which is also shorter in proportion to its 
oral diameter; D. ceras Watson, otherwise apparently its nearest relative, is quite 
distinct, on comparison, 
Dentalium agassizii PILSBRY AND SHARP. 
Plate 4, figure 8. 
Dentalium agassizii Pilsbry and Sharp, Man. Conch., 1897, 17, 'p. 26, pl. 12, figs. 
90-94. 
The following table shows the various stations at which this species has been 
dredged by the “ Albatross ” on her various cruises. 
