218 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
French writers any attempt at a justification of this practice, which 
would seem to have arisen from the fact that Tectura , being pro¬ 
posed — at least in its French form — at about the same time as 
Acmaea , secured a position in the land of its authors which has 
never been successfully disputed, although its rival has undoubted 
right of priority. The arguments have been fully stated by Dali 
and Watson. Bouvier, ’87, p. 22, offers one argument unmentioned 
in either of these statements — the great similarity between the 
names Acmaea and Acmea. The latter was proposed by Hartmann 
in 1821, but, according to Watson (op. cit.), was abandoned by him 
the same year. I have been unable to consult Hartmann’s paper; 
but 1 am informed on excellent authority that his Acmea is derived 
from ’aK/xr; ; Acmaea , on the other hand, comes from ’a/c^atos 
(Rathke, ’33, p. 16), and should therefore stand. 
Some twenty years later this group of ctenidium-bearing limpets 
was itself subdivided. In 1847 Gray, ’47, p. 158, apparently with 
some hesitation, separated from the others those which have both a 
ctenidium and a branchial cordon, giving to this new genus the 
name of Scurria , and restricting the name of Tectura (== Lottia) to 
those which lack the branchial cordon. The name of Lottia Gray 
was thus abandoned to be revived after nearly twenty years. At 
this time Carpenter, ’65, pp. 140-141, erected a new genus for a 
limpet provided with both ctenidium and branchial cordon, but 
having the latter absent in the region of the head. As it appeared 
that this very animal had been figured by Sowerby, ’20-’25, vol. 1, 
pi. 141, as the first mentioned example, and therefore inferentially as 
the type of Lottia Gray, for which Gray himself had mentioned no 
type species, the name given to the new genus was of course 
Lottia. So that Lottia Gray — or more correctly, Lottia Cpr. ex 
Gray — represents but a small part of the original I^ottia Gray. 
It should be said also that some at least of the more recent authori¬ 
ties have reckoned Lottia as a subgenus of Scurria , so that the 
systematic rank of the group is a matter upon which opinions 
vary. And finally it may be remarked that Carpenter, ’60, 
p. 3, had already listed this species, though without a description, 
under the name of Tecturella grandis. This name fell, owing to 
preoccupation. 
In 1834 Broderip described a new limpet-like shell, giving no 
account of the animal, and entitled it Scutella. As this name had 
already been employed by Lamarck, Gray, ’47, p. 168, replaced it 
