JAN. — MAR. 1857.] Pelagian Mollmca collected, 8^-c, 147 
II. Brief notices of Pelagiayi Molliisca collected on a voyage 
from England to Madras, during the niojiths of April, May 
and June 1856. By TVilliam Traill, m. d. 
In throwing together the following observations it was my first 
intention to describe the various Mollusca met with, in the order 
of their classification, beginniag with those highest in the scale, 
but on further reflection I djd not think it would answer any useful 
purpose to do so. Theyaretoofewinnumber to represent the grada- 
tion of the different classe3,which may be more clearly understood by 
a glance at any systematic work on the subject. By adhering rigidly 
to classification I should have very frequently, to reverse the suc- 
cession of events. Moreover, authors are by no means agreed as to 
the exact position in the animal economy, which each group should 
hold : Pteropods for example according to the varying opinions 
of different authors, having successively occupied no less than three 
of the six Classes into which MOLLUSCA are usually divided. 
Upon the whole therefore, I thought it better to note down zoolo- 
gical facts and deductions in the order of their occurrence as be- 
ing a method easier to myself and probably more intelligible to my 
readers. 
In remarking on these animals, I have not been so much actu- 
ated by the belief that some of the species are new to science, 
as by the fact that Pelagic Molluscs in general, and Pieeopods in 
particular, are comparatively little known. Although the indefati- 
gable labours of such men as M. M. Rang, Quoy and Gaimard 
have greatly added to the number of ascertained species, yet in our 
knowledge of their specific distinctions and affinities much remains 
to be accomplished. 
Pteeopods are rarely seen either in public museums or private 
collections ; their mysterious haunts in the unknown depths of the 
ocean render them peculiarly inaccessible to the majority of col- 
lectors ; even the experienced voyager, without some previous know- 
ledge of their habits, would fail to detect any indication of their 
