44 
THE VOYAGE OF H.M.S. CHALLENGER. 
Eschscholtz employed the specific name lamanonii in 1825, and although I am 
inclined to consider that species beyond recognition, still I think that to prevent 
confusion another name should be given to the present species. I therefore propose to 
designate it Atlanta souleyeti. 
In 1852 Costa named a fossil species Atlanta lamanoni. This should also receive 
a fresh name. 
The membranous keel which is one of the distinguishing features of this species is not 
present in any of the dead shells dredged by the Challenger, and probably decays rapidly 
after death. The absence of the carina imparts a peculiar roundness to the last whorl, 
producing a very unusual appearance for a species of Atlanta. 
This species has been considered by Macdonald to belong to the genus Oxygyrus. 
Although the keel upon the last whorl is described as cartilaginous as in Oxygyrus 
rangii and Oxygyrus keraudrenii, the shell itself is of the same vitreous character and 
the operculum the same as that of Atlanta. I think therefore this species must belong 
to that genus, and especially as Souleyet associates it with the recognised species of that 
group. 
Undefined Species. 
1 . Steira lamanoni. 
1825. Steira lamanoni , Eschscholtz, Oken’s Isis, p. 735, pi. v. fig. 3. 
1850. „ „ Gray, Fig. Moll. Anim., vol. iv. p. 101. 
Habitat. — South Sea (Eschscholtz). 
The figure given by Eschscholtz is apparently not at all reliable, and although beyond 
doubt representing an Atlanta , the particular species intended cannot be determined with 
certainty. 
2 . Atlanta helicialis. 
1839. Atlanta helicialis, Sowerby, Conch. Man., fig. 220. 
The shell figured by Sowerby under the above name appears to resemble Atlanta 
lesueurii, Eydoux and Souleyet, more closely than any other. The drawing, however, 
is of so coarse a character that the certain identification of it is quite impossible. 
3. and 4. Atlanta sp. (?). 
Two species are roughly figured by Gray 1 from drawings by Dr. Hooker. This being 
all that is known respecting them, they are quite beyond certain recognition. The 
species represented by figure 7 may be Oxygyrus keraudrenii. 
1 Fig. Moll. Anim., pi. cxvii.c. figs. 2, 7. 
