64 CRETACEOUS GASTROPODA 
Forbes and Hanley, Gray and others, support very much this view. There are in 
fact, especially among the fossil forms of Plewrotoma, species, which have such a 
short spire compared with the last volution, that they resemble most closely the 
slender and elongated species of Conus. The slit near the posterior termination of 
the outer lip is equally not unlike in both. I would recall only Pl. mitreformis, 
Kien. and Con. stromboides, Lam. respectively. Similarities like these and others 
may induce Deshayes to unite Plewrotoma and Conus into one family Conzps, as 
proposed by Woodward. Of course this speaks for itself, since Deshayes does not 
much consent to a further division of the genus Plewrotoma in Lamarck’s sense, but 
I believe it quite impossible to retain such a unity at present, as opposed to the late 
progress in conchological science. It is no doubt remarkable, that those species 
of Pleurotome, which are most nearly like in form to Conus, have the eyes near 
the middle of the tentacles, those with a more elongated and fusiform shell have 
the eyes at the base, like the rvsrvz, and so we have an equal relation to both. 
Gray, in his Guide of 1857, treats the family Pzzvrorourpm, as regards the 
teeth of the radula, with the Cowzp# in his sub-order Toxirera, and this seems 
to be their best place, although I would for my own part not have greater confidence 
in the dentition, than in the other points of relation. H. and A. Adams refer their 
Torritia to the Racutenossa, next to the ruszyz# of the family Moricipx 
to which the true Plewrotome, as regards their form, are no doubt most closely 
related. 
Adams, Gray and others agree in dividing the Pzxvrorourps into three sub- 
families, namely cLATHURELLINE, CLAVATULING and PLEUROTOMINE. 
a. The names craruvreritins and Clathurella, Carp. respectively, have been 
supplied by H. and A. Adams in the corrections (Genera, Vol. IT. p. 654) for the pre- 
viously applied name prrrancrym, as the name Defrancia, Millet, 1826 (1827 ?), 
must be abandoned, because the same had been used in 1825 by Bronn for a 
genus of the Bryozoa. The genera of this sub-family are very much related to the 
Cassrpip#, but most conchologists treat Cythara, Shum. in this  sub-family, 
while others follow Gray’s classification of this genus with the Cussza. . We 
would only here draw further attention to the animal of Cythara, inasmuch as 
it has posteriorly a pointed, not a trunked, foot like most other Pzzvrorouip”; other- 
wise there seems no reasonable ground for a separation. It is of course very desi- 
rable, that many more animals were observed and examined, and it may be then 
found, that several alterations are to be admitted in this sub-family. There is only one 
species in our Indian collection belonging to this group of shells; it will be found 
described as Cythara eretacea, u. sp. 
The genus Clavatula is accepted by Deshayes in his last edition of the Paris 
fossils, III., p. 340. 
b. The czararuzixz have an operculum with a latero-central nucleus. 
ce. The pzaveorournm have an operculum with an apical nucleus; they are 
mostly elongated fusiform shells. 
