.1861.] M. O. A. L. MORCh's review of the VERMETIDiE. 145 



convex ; aperture subovate, pevitreme continuous ; columella sharply 

 truncated. 



Long. 3, diam. 2 lin. 



Hub. Port Essington, Australia. 



This species was discovered by Mr. Jukes at Port Essington. 

 The only other species of the geuus known is that described by 

 Krauss from Port Natal. 



Genus Planorbis, Guett. 

 Subgenus Helisoma, Swains. 



Planorbis (Helisoma) lautus, H. Adams. 



P. testa subovata, fenui, pari altitudine et latitudine, pallide 

 alba, supra profunde et anguste umbilicata, infra planata ; 

 anfractibus '6, celeriter crescentibus, convexiusculis, superne 

 angulatis et angustis, subtus carinatis, subtilissime striis de- 

 cussatis ; apertura subobliqua, subovata, supra anfr actum pe- 

 nultimum surgente, peritremate co7itinuo. 



Shell subovate, thin, the height equalling the width, yellowish- 

 white, deeply and narrowly umbilicated above, flat below ; whorls 

 three, rapidly increasing, rounded, angulated and contracted above, 

 carinated below, decussated by fine striae ; aperture slightly oblique, 

 subovate, extending above the penultimate whorl, peritreme con- 

 tinuous. 



Diam. 2 lin. 



Hab. New Orleans. 



Subgenus Adula, H. Adams. pT*-*"^ 



Testa anfractibus convexis et numerosis, supra profunde umbili- 

 cata, infra convexa; apertura campamdata. 



Shell with the whorls rounded and numerous, deeply umbilicated 

 on the upper, and convex on the under side ; aperture campanulate. 



Ex. P. {Adula) multivolvis, Case. 



This species of Planorbis, which is one of the few having campa- 

 nulate apertures, is so different from the rest in the whorls being 

 numerous and slowly increasing, and in the spire being depressed 

 considerably below the under side, that it appears desirable to sepa- 

 rate it from them. 



6. Review of the Vermetid^, By Otto A. L. Morch (of 

 Copenhagen). (Part I.) 



(Plate XXV.) 



The shells of the Vermetidce are at once to be distinguished from 

 those of the Serpidce by the presence of a spiral nuclear shell and of 

 coucave smooth interior septa ; but these parts are often lost or cou- 



Proc. Zool. Soc. — 1861, No. X. 



