354 MEXICAN BOUNDARY SHELLS— DALL. 



but tbese localities are several bimdred miles to tbe nortbward of Dr. 

 jMearns' station. Tbeie would seem to be no reason wby the species 

 may not extend still farther south in suitable localities among" the 

 mountains of Mexico. Tlie species is reported from near Caraccas, 

 Venezuela, by Jousseaume. The Arizona si)ecimen, like other southern 

 iudividuals, is somewhat smaller tban tl»e best developed northern 

 form, and might be referred to the variety lubricoidesj Ferussac, if worth 

 naming. 



Genus BULIMULUS, Leach. 



Tlie lUilinuili considered in this paper belong to the subgenus Oriho- 

 tomiiott, Crosse and Fischer, as restricted by Pilsbry. If we follow 

 the obnoxious i)ractice of rejecting names which have been used in 

 another gender with a different spelling, as synonyms, we nuist 

 rei)hice the section Leptobyrsus, Crosse and Fischer, by Sonorinn, Pils- 

 bry, for species of the spirifer type. Orthotomium, s. s., practically 

 covers the rest, except a few aberrant elongated pupiform species for 

 which Cooper's name, PUcoJunniaj may be used. 



The Bulimuli of northern Mexico are intimately related to those of 

 the southwestern United States and of the peninsula of Lower Cali- 

 fornia. The fauna of the-last mentioned regiou has something of an 

 insular character, having been in comparatively recent geological time 

 isolated from the continent by an arm of the sea extending in the 

 vicinity of the international boundary line from the Pacific to the 

 Colorado Basin and the head of the Gulf of California. 



Owing to the intercourse between the opposite coasts of the Gulf Of 

 California it has happened that species have been submitted to natu- 

 ralists as coming from the peninsula which really belong to the main- 

 land, but it is by no means certain that there are not a number of 

 common species. I received from Dr. J. G. Cooper, in the same parcel 

 with well known peninsular species and without any distinctive label, 

 a number of specimens of Bidimulus b((ilei/i, which is also represented 

 in the National Museum collection by specimens collected on the 

 peninsula by W. J. Fisher. Dr. Cooper now thinks that his specimens 

 of B. baileyi were collected at Hermosillo, Mexico, and we have speci- 

 mens from northern Mexico, collected by Bailey. So it seems that a 

 doubt is thrown on the peninsular habitat of B. baileyi which it will 

 require further researches to dispel. It must be remembered, however, 

 that B.pallidior is represented by a very slightly modified variety on 

 the mainland as far south as Costa ilica, notwithstanding the fact that 

 its center of distribution is certainly the mountains^ of the peninsula. 



Upiphraf/mophom hachiiaiut was collected by Merrill a little to the 

 south of San Quentin, Lower California (hit. 30^ N.), although it seems 



1 It is hardly necessary to insist on the errors of habitat which assigned this 

 species to Peru aud the South Sea Islands, from which no specimens are Ivuown. 



