144 THE NAUTILUS. 



GENERAL NOTES. 



THE DENTATE VARIETY OF C^u'ilns was first noticed by William 

 Doherty in the Quarterly Journal of Conchology (Leeds), I, p. 344, in 

 1870. He found it at several points near Cincinnati, Ohio, describ- 

 ing the shell as follows: "The 'teeth ' are placed as in Z. multiden- 

 tatus Binn., and vary from one slight shapeless roughening of the 

 inner surface of the outer whorl, to four large elongate teeth, radiat- 

 ing from the umbilicus like the spokes of a chariot wheel. As is 

 usual with gastrodont snails, these teeth attain their greatest de- 

 velopment in the half-grown shell. From the chief locality of this 

 variety I obtained 39 young fulviis, of which 18 or nearly half 

 were more or less dentate, while of 17 adult fulvus from the same 

 place, one had in the next to the last whorl a single tooth, much 

 flattened and eroded, while all the others were toothless. Hence I 

 suppose that the teeth are gradually worn away by the motions of 

 the animal. In Z. multidentatus, rows of teeth appear at an early 

 age, and as often as the shell grows a quarter of a whorl a new row 

 i ] reduced, while the earliest is worn away. So the shell grows to 

 maturity, always having three or four rows of denticles. In this 

 variety oi fulvus, however, this process seems to cease long before 

 the shell reaches maturity and the last whorl is thus left without 

 teeth." 



POLVGVRA RICHARDSONI var. LiNGUALis n. var. Similar to the 

 type in ^ize (alt. 5-5/2, di.nn. 10-11*4 mm.), very smooth and 

 glossy, depressed above and below, though the base is convex, pro- 

 jecting downward as far as or below the basal lip ; umbilicus filled 

 by the preceding whorl <-xcept for a minute axial puncture ; parietal 

 fold of the aperture decidedly longer than in richardsoni, extend- 

 ing to within one-half or one-third of a millimeter from the broad 

 lamina on the o Jter lip. Whorls +y z (instead of 5). Rosario, 

 near Mazatlan, N. W. Mexico, collected by M. A. Knapp, received 

 from W. J. Raymond. H. A. PILSBRY. 



PLANORBIS IJILATATUS Gould has recently been found by Hori'. J. 

 D. Mitchell in the Guadalupe river, in Victoria Co., Texas. This 

 is further south and west than previously recorded. 



