ACADEMY OF SCIENCES. 21 
with atooth. ©. maculatum. Depressed, five spires, hardly striated, upper 
lip reflexed, tooth careniform. Fulvous with brown spots,’’ agrees best with 
multilineata, for he does not state that it has a tooth ‘‘on the spire,’’ as in 
Odotropis, but a ‘‘ careniform ”’ ridge on the lower (not ‘‘inner’’) lip. Thus 
Mr. Tryon’s statement that he figured albolabris as type in Mss. is intelligible, 
showing that the tooth referred to was not on the parietal wall as usually 
understood.* We must then suppose that he made the genus to include the 
species he before placed in Heltx. 
It appears most proper, if we adopt any of Rafinesque’s names, to use 
those published before 1825 in preference to later ones, invented after his 
mind became affected. His earlier writings are as clear as those of most 
naturalists of his time, and from his allusion in some places to unjust sup- 
pression of his descriptions in Europe, we may suppose he would have done 
better after 1825 but for his unhappy condition. On this account the name 
Odotropis having an excellent description given with it would be far preferable, 
if he had not unfortunately,omitted to mention a type species. As it is, it 
can only be used for a section, as done by me in 1868. 
As to the distinctness of this genus from Helix as defined before, there can 
be no doubt, and it is still more different from the Pomatia group. The large, 
typical species all differ definably in shell, jaw and lingual teeth, as well as in 
the form of the animal, which has the foot less expanded. The nearest 
approach to Helix, in shell, is seen in 0. multilineata and O. profunda, but 
their bands and jaws are quite different. As subgenera it includes Aplodon 
Raf., Polygyra Say?,t Stenostoma Raf., Triodopsis Raf., Dcedalocheila Beck. 
Mesodon Raf. only differs from Odotropis in absence of a parietal tooth and 
of umbilicus, and Ulostoma is synonymous with Mesodon, having a tubercle 
on the lower lip. Trophodon Raf. is doubtfully distinct, connecting Odotropis 
and Triodopsis, while Xolotrema includes only the imperforate species of the 
last, connecting it with Stenostoma. é 
The lip and teeth alone furnish only subgeneric characters, and the umbilicus 
is scarcely of specific value. While some of the above divisions approach 
nearer to Helia in internal characters, their shells are still more different. 
M. Townsendiana var. ptychophora A. D. Brown, Journ. de Conchyl. 
1870, p. 392. =H. pedestris Gld. (part, animal excl. smooth var.) 1846. 
= H. Townsendiana var. Bland & Cooper, Ann. N.Y. Lye. VII, 362, and var. 
minor Tryon, Mon. Terr. Moll. of U. 5. 
Hab. Montana and Nebraska, Rocky Mts. 
It seems yet unsettled whether this species belongs to Arionta or Mesodon, 
and I have been unable to obtain living specimens for comparison. Mr. 
*Mesodon Raf. (1819?) 1831, type H. thyroidus Say, teste Ferussac (from specimens ?), 
albolabri steste Tryon from Raf. Mss. ‘‘ Type elevata Say,” teste Gray, but this was probably 
a type of Trophodon 1818, which differed in the ‘‘ upper lip notched.” Gray, however, fol- 
lowed the strictrule of adopting the first recognizable species named in Ferussac’s catalogue’ 
= Odomphium Raf, 1831 (umbilicate group of Mesodon). 
Raf.’s Mss. figure of ‘‘ M. leucodon thyroide”’ is certainly thyroidus, but called ‘‘ spotted,” 
and the trinomial term used indicates that it was not his original type. 
7This name though anterior, is inapplicable to all the species. 
