2 THE NAUTILUS. 



and again appears, curving outward, at about the middle of the col- 

 umella as the laraella-like margin. 



One specimen has a conspicuous groove in the middle of the 

 peripheral white band, and although very uniform, it is undoubtedly 

 due to injury. 



The species is well figured both by Adams and Pilsbry. It has 

 been recorded from northeast Australia, Sandwich and other islands 

 of the Indian and Pacific oceans. Type loc, Mauritius. 



A NEW FLOBIDIAN AMNICOLA. 



BY WILLIAM n. DALL.' 



Some fresh-water marl from a swamp at the south end of Lake 

 Panasoffkee, six feet below the present surface, collected by Mr. A. 

 M. Harper, was recently submitted for examination by Mr. C. A. 

 Davis, of the U. S. Geological Survey. It contained a number of 

 species known to live in the region, in determining which I had the 

 kind assistance of Dr. H. A. Pilsbry. One species which will prob- 

 ably be found living, later on, seems to be new. 



Amnicola harperi n. sp. 



Shell minute, depressed, rapidly enlarging, with about three 

 whorls ; surface smooth, except for faint incremental lines, almost 

 polished, the whorls are full and rounded,- almost circular in section, 

 thus forming a deep suture ; umbilicus wide and deep, the whorl 

 evenly rounding into it ; aperture nearly circular, with a faint angu- 

 lation where it touches the preceding whorl, the margin entire, 

 simple, slightly expanded, the plane of the aperture slightly oblique. 

 Height of shell 1.2, diameter 1.3, diameter of aperture 0.7 mm. 



This little shell looks like a very minute replica of Valvata sin- 

 ccro, and if it were not for the slight angulation of the aperture would 

 have been referred to Valvata. No Lymnaeas were found in the 

 marl. The species associated with A. harperi were : Pisidium sp. ; 

 Succinea sp. ; Physa heterostropha ; Ancylus tardus ; Planorbis tri- 

 volvis, parvus, dilatatus, and alahamensis var. avus ; Paludestrina 

 tnonas Pils., and brevissima Pils. ; Amnicola johnsoni and augusiina 

 of Pilsbry ; Vivipara georgiana Lea and Goniohasis papillosa Anth. 



* By permission of the Director of the U. S. Geological Survey. 



