two Genera of Molluscous Animals. 33 
which are picked up dead. The small species for safety should be glued on 
blackened card. I do not observe that the fissure is always dorsal; in my 
specimens it is either lateral or ventral. 
Of the place of Dentalium in the natural system I will not venture to speak 
at this moment, though perhaps we shall not do wrong, in the present state 
of our knowledge of the Mollusca, in placing it near the great family, or, I 
should rather say, great tribe of Linnzean Patella. In its anal opening it 
resembles the genus Fissurella, while the apical fissure represents the poste- 
rior marginal rima of Emarginula. 
The substances figured by Mr. Sowerby in his accurate illustrations of the 
Genera of Shells, fig. 9, are in no way connected with Dentalia, though I 
do not pretend to determine their real nature. "Their closed mouth and the 
connecting corneous ligaments are very curious. I have lately dredged up, 
among sea-weeds, numerous specimens of an animal (Ozkodomicus, Guild.) 
much more analogous in outward look to the true Dentalia. "The habitacu- 
lum is diaphanous, tubiform, vitreous, slightly bent, symmetrical, having the 
termination softer but not attenuated. It does not possess the hard calca- 
reous body of the shells before us; but if Cuvier himself had received the 
empty habitacula, he might have thought them good Dentalia. The animal, 
however, is not affixed, but is closely related to Nereis. It is a most singular, 
active and entertaining animal in its captivity, and shall be fully noticed here- 
after. 
MOLLUSCA. 
Statio generis in systemate adhuc dubia sistit, at forsitàn prope Emarginulas. 
Genus. DENTALIUM. Auctorum. 
Animal arenicolum, valdè elongatum, testæ figuram exhibens, dorso arcuato. 
Corpus anticè truncatum, posticè mollius, subdiaphanum, musculis lateralibus 
elongatis. 
Caput anticum, absconditum. 
Tentacula cervicalia, numerosa, elongata, subcapitata, apicibus suctoriis ? 
Pallium tumidum, plicatum, pedis basin cingens. 
Branchie duo, pectiniformes, abdominales ? 
Pes terminalis, magnus, extensus, subcylindricus, subattenuatus, vermiformis, 
VOL. XVII. F 
