PHYSA, 



81 



No. 9096 of the collection was presented by 

 Prof. Agassiz from the original lot collected by 

 him. Gould's description and figure arc copied 

 above. 



It has also been catalogued from Michigan. 



The lingual teeth of the lateral rows of Fhysa 

 vinosa are represented in Fig. 138. 



Fig. 138. 



Lingual dentition of 

 Physa vinosa. 



Fig. 139. 



Physa 



ancillaria. 



Pltysa ancillaria. Sat. — Shell heterostrophe, sub-globose, pale 

 yellowish ; whirls rather more than four, very rapidly attenuated ; spire 

 truncated, hardly elevated beyond the general curve of the 

 surface ; suture not impressed ; aperture but little shorter 

 than the shell, dilated ; labrum a little thickened on the 

 inner margin. Length more than one-half of an inch. 



The spire of this species is unusually short, truncated at 

 tip like the Paludina decisa, nob. ; and the suture is so incon- 

 spicuous as to give rise to the name which I have chosen for 

 it. My brother, B. Say, obtained it in .the Delaware River, 

 near Easton, and Mr. Jessup collected numerous specimens 

 in the Connecticut River, above Hartford. It may be dis- 

 tinguished from P. hetei-ostropha, nob., by the shorter and 

 truncated spire, incons.picuous suture, as well as by the more obtusely 

 rounded junction of the labrum with the base, and by the general form. 

 (Sn//.) 



Physa ancillaria, Sat, Jour. Acad. Nat. Sc. V, 124 (1825) ; Binnet's ed. 

 114.— Haldeman, Mon. 27, pi. iii, f. 1-10 (1843).— Gould, Invert. 

 213, f. 142 (1841).— Adams, Shells of Vermont, 154 (1842).— De- 

 Kat, N. Y. Moll. 78, pi. V, 90 (1843).— Chemnitz, ed. 2, 20, pi. xii, 

 f. 12-13.— Chenp, Man. de Conch. II, 480, f. 3550.— Anon. Can. Nat. 

 II, 211, fig. (1857). 

 Physa obesa, DeKat, N. Y. Moll. 78, pi. v, f. 86 (1843). 



This species appears to range from Xew England to Louisiana. 



It is very numerous in the Delaware River at Burlington, on 

 the muddy shores left bare at low tide. The animal burrows 

 into the mud as soon as left bj the water, and remains concealed 

 until its return. On the piers of the w^harves it crawls down- 

 wards with the fall of the tide and upwards again as it rises, 

 thus keeping always near the surface. 



