THE NAUTILUS. 105 



Unio crassidens Lamarck. obliqua Lamarck. 



Pleurobema aesopus Green. ebena Lea. 1 



Quadrula plicata Say. tuberculata Rafinesque. 



undulata Barnes. metanevra Rafinesque. 



heros Say. Vivipara intertexta Say. 



lachrymosa Lea. Campeloma integrum DeKay. 



pustulosa Lea. subsolidum Anthony. 



pustulata Lea. Polygyra multilineata Say. 



trigona Lea. 



The last was found to be a common inhabitant of the islands in 

 the river and in the woods bordering the Iowa side of the river. 



At Carroll Creek, ten miles from Savanna, Mr. C. C. Adams, of 

 the University of Chicago, collected the following species, all being 

 very common : 



Amnicola limosa Say. Physa integra Haldeman. 



Physa gyrina Say. Succinea ovalis Say. 



A NEW FOSSIL ASHMUNELLA. 



BY T. D. A. COCKERELL. 



ASHMUNELLA THOMPSONIANA PECOSENSIS subsp. nov. 



Small (diam. max. 12, min. 10.5 ram.) ; last half of last whorl 

 very distinctly transversely ribbed, recalling A. altissima ; lip and 

 teeth strongly developed, basal tooth single. 



Hob.: Valle Ranch, Pecos, New Mexico, in a light reddish deposit 

 of uncertain age, Nov. 30, 1902. (T. D. A. and W. P. Cockerell.) 

 The commonest shell in the deposit is Pyramidula strigosa cooperi. 

 Vallonia cyclophorella is also abundant. 



Last year my wife collected a dead shell of a recent Ashmunella at 

 the old Pecos Pueblo, which is only a few miles from the Valle Ranch. 

 It is A, thomsoniana, with max. diam. 13.5 mm., basal tooth single. 

 There is no sign of the ribbing of the fossil form. 



1 This species is called " nigger-head " by the fishermen, and is considered 

 the most desirable shell for the cutting of pearl buttons. 



