16 THE NAUTILUS. 



Several specimens, more or less crushed, of a large Lima are 

 among the forms collected. This species belongs to the general type 

 of Lima excavata Fabr., L. goliath Sby, etc., and reaches to a 

 length of four and a half inches. The valves are brilliantly polished, 

 and in the middle part unsculptured, the anterior and posterior 

 thirds are finely radially grooved with shallow grooves of which the 

 outer slopes are less steep than the inner ; the incremental lines, 

 obsolete elsewhere, appear in the channel of the grooves and cross 

 striate it here and there, giving the effect of obsolete punctation. I 

 may add that close to the impressed area of the shell there are two 

 or three coarser, deeper radial grooves. The species differs from 

 the South Pacific and. all other forms of its group known to me in its 

 much finer and more delicate sculpture and brilliant polish. I await 

 more perfect specimens before trying to figure it, but would propose 

 the name of Lima Hamlini for the species in honor of Mr. Homer 

 Hamlin C. E., Asst. City Engineer of Los Angeles, who is much 

 interested in the geology and paleontology of the region, and has 

 made valuable studies of the southern California Tertiary. The 

 specimen in hand was kindly forwarded for examination by Dr. R. 

 E. C. Stearns. 



A REVISION OF THE PHYSJE OF NORTHEASTERN ILLINOIS. 



BY FKANK C. BAKER. 



While working up the fresh-water mollusks of the Chicago area 

 for a report on the Mollusca, the genus Physa came up for considera- 

 tion, and the chaotic condition of the group, judging by the conflict- 

 ing opinions of conchologists, seemed to warrant a somewhat critical 

 revision of the species found in northeastern Illinois, and incidentally 

 of northern Illinois. The best-known species, heterostropha, is little 

 understood, and seems to be more frequently confounded with gyrina 

 than with uny other form, excepting, perhaps, Integra. 



A large collection of Physidae, from different parts of the United 

 States as well as from northern Illinois, has been examined, and the 

 writer believes that all of the species found within the area have been 

 elucidated. It is very probable that there are but ten or fifteen valid 

 species of Physa in the United States, six or seven of which are to 

 be found in the northern part of this region east of the Rocky 

 Mountains. 



