94 THE NAUTILUS. 



Tornatina cwialiculata (Say). Fairly common at 5. 

 Cylichna oryza (Totten). Several specimens at 5. 

 Melampus lineatus Say. Most common at 2. 

 Alexia myosotis (Drap.) Fairly common at 3. 



On a tramp up and down the western end of Long Beach 

 point, Long Island, I picked up the following interesting 

 forms, besides forty-eight of the commoner species: 



Yoldia limatula (Say). 1 valve. 

 Area ponderosa Say. 3 valves. 

 Astarte castanea (Say). Common. 

 Tellina tenella (Verrill). 1 valve. 

 Tellina versicolor De Kay. 2 valves. 

 Barnea cost at a (Linne). 1 valve (fragment). 

 Cavolina telemus (Linne). 1 specimen. 



DESCRIPTION OF A NEW SPECIES AND VARIETY OF PLANORBIS 

 FROM POST-GLACIAL DEPOSITS.* 



BY PRANK C. BAKER. 



Planorbis parvus urbanensis n. var. PL VII, figs. 4-6. 



Shell differing from parvus by having a round aperture, 

 the last third of the body whorl being depressed below the 

 general level of the spire, deeper sutures, channelled in most 

 individuals, and a deeper umbilical region. The body whorl 

 has not quite as great transverse diameter as in typical parvus. 

 In parvus (pi. 1, figs. 1-3), the whorls are typically in the same 

 plane, the aperture is oblong or long ovate and the sutures are 

 impressed but not channelled. The umbilical region is also 

 less impressed and has a "reamed out" appearance. 



Height at aperture, 1.00; greatest diameter, 3.00 mm. 

 Holotype. 



Height at aperture, 1.00; greatest diameter, 3.00 mm. 



* Contribution from the Museum of Natural History, University of Illinois, 

 No. 1. 



