Green's new species of Achat ina. 47 



mens the indication of a second ridge near the anterior end; 

 both these ridges are alternately raised and depressed — 

 periostracha much wrinkled by the striae, of a light horn 

 colour, and remarkably glabrous — in old and young speci- 

 mens it is darker than in the perfect shell — and the young 

 are often beautifully rayed and spotted with brown — nacre 

 commonly white, pearly, and undescent — teeth moderately 

 thick — length about two inches — breadth about four. 



This shell inhabits probably all our western waters; and 

 it is a little remarkable that Prof. Rafinesque, who has de- 

 scribed and figured so many of the Unionise, should have 

 omitted this remarkable species. I found eight or ten of 

 these shells in the rivers in the neighbourhood of Pitts- 

 burg. In old shells the anterior margin is often produced 

 and truncated — and the young specimens seem to be pecu- 

 liarly liable to a preternatural enlargement of some portions 

 of the shell, more than others. 



Description of two neiv species of Achatina, from the 

 Sandwich Islands — with some remarks on the Ti, ths 

 plant on ivhich these shells are commonly found. By 

 J. Green, A. M. Prof, of Chem. in Jeff. Med. College, 

 Read May 14, 1827. 



ACHATINA Stewartii. 



A testa -sinistrorsa — ovato — oblonga — lutescente, minu- 

 tissime striata — colore varia, nunc unicolore, nunc 

 diversissime faciata — collumella rosea — lahro tenui— 

 intus albido. — Plate 4, figs. 1, 2, 3, 4. 



Stewart's Achatina. — Shell heterostophe — conical — 

 oblong — about one inch in length and half an inch in diam- 

 eter — whorls six or seven, rounded and marked with nu- 

 merous oblique and delicate striae — apex rather obtuse and 



