REPORT ON THE PTEROPODA. 
39 
Dimensions . — 1’5 mm. in diameter. 
Operculum and animal unknown, but almost certainly like those of the two other 
species here enumerated. 
Habitat. — Kino Osirna (Japan), A. Adams. 
# 3. Agadina, n. sp. (PL I. figs. 15, 16). 
Shell smooth, globular; spire short, but projecting beyond the last whorl; three 
bulging whorls, overlapping, and somewhat obliquely twisted ; aperture rounded, oblique, 
with margins slightly expanded ; umbilicus almost suppressed, covered by the last turn, 
which exhibits a keeled projection over this spot. 
Operculum horny, circular, multispiral, with four and a half whorls, gradually 
increasing in a left-handed spiral ; the surface of insertion very large. 
Animal. — Without fins, resembling that of Agadina stimpsoni, but with the lobes 
of the velum more pointed, and the foot more elongated anteriorly. 
Challenger Specimens. — I. Living. 
Station 175, August 12, 1874 ; Fiji to Raine Island ; lat. 19° 2' S., long. 1 77° 10' E. 
Station 216 a, February 16, 1875 ; north of New Guinea; lat. 2° 56' N., long. 
134° 11' E. 
II. Deposit shells. 
Station 120, September 9, 1873; off the coast of South America, between Pernam- 
buco and Bahia; lat. 8° 37' S., long. 34° 28' W.; depth, 675 fathoms; bottom, 
red mud. 
Since this form, like the two before it, is only the larval form of some Gastropod, 
there is no occasion to give it a specific title. 
It is evident that these species cannot be ranked among the Pteropods. The absence 
of fins, the presence of a four-lobed velum when the shell has already three whorls on its 
spire, the presence of a foot with a creeping surface, are facts sufficient to demonstrate 
that we have here to deal with pelagic larvae of streptoneural Gastropods. 
This shows very distinctly the dangers of elaborating a zoological system without due 
regard to comparative anatomy. 
Woodwards 1 statement that the true Limacinidae may be distinguished by their 
left-handed twisting “ from the fry of Atlanta, Carinaria and most other Gastropods ” is 
thus quite inexact. 
What enables one always to distinguish the Limacinidae from the larvae of Gastro- 
1 Manual of the Mollusca, 1856, p. 207. 
