NO. im. 



rROCEEDIKGS OF THE NATIONAL MUSEUM. 355 



to be a cliaracteristic species of the mountain peaks of northern Mex- 

 ico. It is evident, therefore, that it will not do to be dogmatic about 

 doul)tful localities connecting the mainland and peninsular faunas. 

 The isolation of each by desert tracts of lowland is almost as complete 

 as if it were by water, but a thorough search will probably reveal a 

 number of species common to both regions. 



Although the Boundary Commission at the northern border of Lower 

 California did not reach the mountains where the peninsular fauna 

 flourishes, it seems permissible here to discuss some species of the latter 

 which are genetically connected with others touched on in this report 

 and belong to the same faunal region in its broader sense. 



Since this paper was originally wiitten (January, 1895) Mr. Pilsbry 

 has proposed a revision of the American Bulimuli, based on the typical 

 species of each group and especially the characters of the nepionic 

 shell. This revision ' has been utilized and the names adopted in it 

 have been used here in place of those previously current. 



In discussing the land shells of Lower California, Dr. J. CI. Cooper 

 has expressed certain opinions to which it seems necessary to refer, as 

 otherwise some misconceptions might be perpetuated in spite of Mr. 

 Pilsbry's revision. The subgenus Rhodea was created by the brothers 

 Adams in 1858 for the Achatlna californica of Pfeiffer. The type is 

 now known to inhabit the mountains of New Grenada and the adjacent 

 region and to have no relation to the African genus Columna, Perry, 

 to which it was referred by Adams as a subgenus. An excellent review 

 of the group (raised to generic rank) containing good figures of the 

 species was published by H. Crosse,^ and it is also treated of in the 

 great work on the Mexican land shell fauna by Crosse and Fischer. 

 For historic details the reader is referred to these monographs. 



The principal characters of Rhodea consist in its elongated parallel- 

 sided form, smooth, dome shaped, Steno(jyra-like nucleus, the distinct 

 sutural keel more emphasized in the later whorls; the constriction of 

 the last whorl, medially; the gyrate columella in the last whorl or two, 

 making a pervious axis; the channel behind the columella which forms 

 a rounded prominent fasciole encircling the axis, and in the adult ter- 

 minates in an angular sinus in the otherwise continuous peristome. 

 The anatomy is helicoid, the jaw is furnished with a few strong, distant 

 vertical ribs, and the animal is ovoviviparous, like Stenogyra. One of 

 the species is sinistral, the others dextral, but all are very much alike 

 and sculptured only with transverse striations. 



The California Academy of Sciences has sent several expeditions 

 into the adjacent parts of Mexico and the peninsula of Lower California, 

 during which interesting land shells were collected by Dr. G. Eiseu and 

 other members of the party. These have been described in the publi- 

 cations of the academy by Dr. J. G. Cooper. Among them were some 



' The Nautilus, IX, No. 10, pp. 112-115, Feb., 1895. 

 '^ Journ. de Concliyl., XXIV, p. 5, 1876. 



