OF CONCHOLOGY. 153 



3. Amnicola Panamensis, Tryon. 



Collected at the roots of aquatic plants in a swampy pool near 

 Javali, in the Chontales, at an elevation of 1750 feet. 



4. Tryoxia ornata, Morelet. 



On the muddy shores of Lake Nicaragua and in the pools by 

 the margin of the same, La Playa, Grenada. 



Of the desiderata to our knowledge of this genus I can only 

 furnish that of the operculum, which is corneous, thin, subspiral, 

 and radiately marked. 



T. ornata is the third species of the genus ; the others inhabit 

 California. 



5. Neritina Listeri, Ch. 



Very abundant on the rhizomes of aquatic plants throughout 

 the river San Juan. In Greytown harbor, where, this species 

 and Pla7i07'bis tuniidushve, the water is alternately brackish and 

 fresh, according as to whether the tide is flowing or ebbing. 



6. Neritina virginea. Lam. 



With Cyrena soUda, Phil., on sandy bottom, brackish water 

 pools, Punta- Arena, Greytown ; nidifying on dead shells of 

 Cyrenoe and on each other ; very abundant. Also at Salt Creek, 

 Costa Rica, and Boca del Toro, Panama. This species is truly 

 estuarine. 



[Neritina intermedia, Bred. 



On the bottom of a small fresh-water stream by the railway 

 terminus, Panama City.] 



7. Tebennophorus auratus, Tate. 



^w/maZ elongated, slender, attenuated behind, convex, shining, 

 smooth ; mantle reaching to nearly the edge of the foot, from 

 which it- is separated by a groove ; yellowish-grey, with numer- 

 ous small white and gold spots, and fewer and larger black ones, 

 the last forming a black streak on the upper lateral margin ; 

 foot narrow, extending a little beyond the mantle, pointed be- 

 hind, truncated in front, where it is of a reddish-yellow color, 

 other portion whitish-grey ; tentacles four, upper black, one-tenth 

 of an inch in length, lower tentacles very short. 



Dimensions. — Extended length, -8 inch; breadth when ex- 

 tended, -1 inch ; respiratory orifice, from the front, -15 inch ; 

 contracted length, -5 inch. 



