MOLLUSCA 131 



European species; but Ancey, a French naturalist, protested that 

 some of them represented perfectly distinct kinds. His views 

 were at first received with ridicule, until Dr. V. Sterki of Ohio took 

 the matter up, and in 1893 published a revision of the genus. 

 He out-Anceyed Ancey, and was even able to show that a common 

 European species had been overlooked, and provide it with a 

 name. It was one of those cases where nobody can see a thing 

 until it is pointed out; then every one can see it. There are four 

 native species of Vallonia widely distributed in Colorado, and a 

 fifth much less common. Their characters and localities are given 

 in Henderson's work, University of Colorado Studies, XIII, No. 2. 

 In 1864 Dr. E. S. Morse gave the name Pundum (a point) 

 to a genus of very minute snails found all around the world in 

 northern regions. They come near satisfying the definition of 

 a point as that which has neither length nor breadth, the typical 

 species being only a little over a millimeter in diameter. The 

 jaw is peculiar for consisting of a series of distinct subquadrate 

 plates, instead of a solid arched structure as in more ordinary 

 snails. It is possible to extract the jaw and lingual membrane 

 from these minute animals by crushing the shell, and subjecting 

 the soft parts to the action of a solution of caustic potash, which 

 dissolves the tissues, leaving the chitinous parts intact. The 

 excessively minute teeth on the lingual membrane have been 

 estimated to number about 4,400. The common European 

 species of Pundum has been appropriately called P. pygmaeum, 

 and it is generally supposed that the same snail exists in Colorado 

 and other parts of North America. There are however some 

 differences, so that the American shell has been treated as a sub- 

 species, P. pygmaeum minutissimum of Lea. Morse counted 

 only about 1 ,400 teeth on the lingual membrane, but not enough 

 counts have been made to determine whether there is any con- 

 stant difference in this respect between European and American 

 specimens. The first Colorado specimen of this little snail was 

 found many years ago in Custer County. About fifteen years 

 ago Mrs. Cockerell obtained others at Tolland, by collecting a 

 quantity of debris from under the aspen trees, and sorting it on 

 a sheet of paper. By such means it is possible to see the shells, 

 but it takes extraordinarily sharp eyes to detect them on the 

 ground in the forest. 



