332 PROCEEDINGS OP THE CALIFORNIA 



Although colors alone are usually unreliable as subgeneric characters, I am 

 inclined to consider them as such in the case of these and some allied species, 

 from their apparent connection with important organs. In fact the band, so 

 constant in this large series of species, takes precedence of considerable variety 

 of form, for the variations in outline, umbilicus, and peristome, though great 

 in the extremes, are so gradually shaded and blended together in the whole 

 series that no well-defined generic divisions can be founded on them, though 

 useful for the minor grouping. The umbilicus especially is variable even in 

 specimens of the same species, those from southern and arid regions being often 

 nearly imperforate, and more conical than others. 



Several Mexican species belong to the same series, such as FL Rkmondii Tnjon, 

 H. GrsrsEOL\ Pfoijf, aid B. B3xl\^dieria.ma Moric, the two last extending to 

 Texas. Others, as H. Humboldtiana Fin/., scarcely differ from the typical 

 Pomatia in form. I would, however, exclude the true Hygromias associated with 

 these by Tryon. I would also exclude the plain or variegated species of Lower 

 California, which approach nearer to Polymita. It must be observed that many 

 of our species approach in form to others of allied groups, so that if we overlook 

 characters of color aud surface, we will be inclined to place in the same groups, 

 Nos. 40 and 52, 24 and 32, 29 and 47, etc. Even in color Nos. 32 to 35 show an 

 approach to the group of Lower California, but seem more closely allied to our 

 series, having merely a geographical affinity to the former. Size is of little 

 value, even as a specific character among the land shells, nearly all the species 

 furnishing specimens twice as large as others of the same kind. The propor- 

 tions of height to breadth are more reliable, but not constant. 



The subgenus or division characterized by the band is scarcely distinguish- 

 able as a whole from the typical Helix, (type pomatia) of Europe, though the 

 extremes vary greatly, simulating the three or more foreign genera to which 

 various authors have attached them.* 



Our species are distinct enough among themselves when the true specific 

 characters here given are noted, though occasionally hybrids undoubtedly occur. 

 Dr. W. Newcomb has raised many specimens in his garden in Oakland, com- 

 bining the characters of Nos. 24, 25, 29, 31, and 43, in such manner that it is 

 often impossible to determine which they belong to. Yet their natural locations 

 are usually so widely separated that only occasionally can hybrids occur in a 

 state of nature, and where several do inhabit one locality, as 24, 27, 28, 46 do at 

 Santa Cruz, though nearly allied, intermediate forms are not found. Some of 

 the so-called species are, however, scarcely more than hybrids or varieties, but 

 the names are retained as indicating their differences, though almost every spe- 

 cies is divisible into varieties as well marked or better. Thus the specimen de- 

 scribed on p. 260 of this volume (from Mount Diablo) seems to be a hybrid 



'Extreme specimens of //. arrosa found by Mr.Gabb in Mendocino County, Gal., its northern limit, 

 and also one of 11. redimita found in Alameda County by Jlr. Holder, have exactly the form of 

 H. pomatia, and in each case have one and a half whorls less than the types, Indicating perhaps 

 that the usual forms found here are higher developed than the type of the genus. (A genus Pomatia 

 has also been founded on this type of the Linusean genus Helix.) 



Aglaia was used by Escholtz, 1825, in Acalephae, by Swainson, 1827, in Birds, and by Eenierin 

 Philiuidse, before Albers adopted it in this order! ! 



