1913.] NATURAL SCIENCES OF PHILADELPHIA. 391 



of them is fully mature. I think, therefore, that "Magdalena Bay" 

 should undoubtedly be taken as the type locahty of H. areolata. 

 Further information is needed to determine the exact place in that 

 neighborhood where shells agreeing with Pfeiffer's figures 10-12 

 (my text-fig. 2) are found, whether on the mainland or on Margarita 

 Island. None of the shells before me are exactly localized. They 

 bear the general locality "Magdalena Bay." It is evident from the 

 five lots seen that different colonies vary in size, elevation, and degree 

 of maculation.* Pfeiffer's type and the specimens received from 

 Sowerby are more depressed than most other lots. 



The more northern localities cited for areolata by Dr. Cooper and 

 others pertain, I believe, to forms of the levis group, which is known 

 to occur from Asuncion Island northward, a region where areolata 

 does not occur. The known areas of levis and areolata are separated 

 by a long reach of coast whence no land snails are known. The 

 Natividad Island specimen I dissected as areolata (1898) is a form of 

 veatchii. With the exception of var. exanimata Cooper, areolata is 

 not known to occur elsewhere than about Magdalena Bay, where it 

 inhabits one of the dryest regions in the world. 



The shell is opaque white, with ochre-lirown bands broken into 

 square spots, very variable in number and arrangement, as shown 

 in the figures. In one lot, markings are absent, or indistinct and 

 corneous. The embryonic whorl is grayish corneous or yellowish 

 corneous. The columella varies from simple to distinctly toothed. 

 The size varies. 



Alt. 



(1) Var. arida (pi. XVI, figs. 39, 40, 41). Small, thin, white, or 

 having sparse markings of typical form and color; lip hardly or not 

 thickened, columella concave, not toothed. Descent of the last whorl 

 to the aperture deeper and longer than in any other form of areolata. 



Alt. 14, diam. 18 mm.; 4| whorls. 

 " 15, '' 181 '' 4f '' 



Magdalena Bay (R. C. Macgregor). 



*The locality "Margarita Bay, Newcomb," quoted by Dall, must have been 

 an error or slip of Newcomb's for Magdalena Bay, or more likely Margarita 

 Island, which guards the bay, since, so far as I can learn, there is no Margarita 

 Bay on that coast. 

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