30 THE NAUTILUS. 



7. POLYGYRA (TniOUOPSIs) TRIDENTATA FRAUDULENTA Pilsbry. 



A single specimen of this subspecies was collected by Mr. Woodruff. 

 Its radula differed considerably from that given in Birmey's Manual 

 of American Land Shells (p. 292), where 40-1-40 teeth with 12 

 perfect laterals is given. The present specimen had 27-1-27 teeth 

 with 11 perfect laterals. The 17th tooth had a bifid inner cutting 

 point, but all before it were simple. The 13th tooth showed a 

 decided modification. The jaw was as usual, with 12 rather stout 

 ribs. 



8. POLYGYRA (TRIODOPSIS) INFLECTA Say. The specimens col- 

 lected were of the usual form. 



9. POLYGYRA (STENOTREMA) MONODON FRATERNA Say. The 

 specimens examined had 31-1-31 teeth on the lingual membrane 

 with 10 perfect laterals, and the 13th tooth had a bifid inner cutting 

 point. 



10. POLYGYRA (STENOTREMA) HIRSUTUM Say. The specimens 

 obtained were of the normal form. One specimen measured 8 mill, 

 in greatest diameter. The radula was as given by Binney, 22-1-22 

 teeth with 10 perfect laterals, and the jaw had eight ribs. 



11. PYRAMIDULA ALTERNATA Say. The specimens collected are 

 rather coarsely striated (or ribbed) and approach var. mordax 

 Shuttl., but the ribbing is not quite as strong as in that variety. 



12. PYRAMIDULA PERSPEOTIVA Say. Among the specimens ob- 

 tained was one measuring 10 mill, in greatest diameter. 



13. LIMN^A HUMILIS Say. A number of specimens were col- 

 lected in the moss under a waterfall. Mr. Woodruff reports finding 

 all the specimens out of the water. 



It was remarkable that so few species of mollusks were found, and 

 also that the species were so few in individuals. Mr. Woodruff' says 

 that a part of the region is made up of sandstone and conglomerate, 

 and this may account for the great paucity of molluscan life. Mr. 

 Woodruff' searched diligently many times, particularly for the 

 smaller forms, and states that at no time did he find more than one 

 shell at one time, all seeming to live solitary lives. 



ISAAC LEA DEPARTMENT. 



[Conducted in the interest of the Isaac Lea Conchological Chapter of the Agassiz Associa- 

 tion by its General Secretary, Mrs. M. Burton Williamson.] 



Through the courtesy of Mr. Herbert Lowe, the writer had the 

 pleasure of meeting our former member, Mr. Edward W. Roper of 



