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2. Description of a new genus of the Family Melaniana, 
AND OF MANY NEW SPECIES OF THE GeNUS MeLANIA, 
CHIEFLY COLLECTED BY HUGH CUMING, Esq., DURING HIS 
Zoological Voyage in the East, and now first de¬ 
scribed. By Isaac Lea and Henry C. Lea, Phila¬ 
delphia *. 
Genus Pachychilus f. 
Testa conica. Apertura ovata, basi integro. Labrum crassum. 
Columella superne incrassata. Operculum suborbiculare, corneum. 
The genus Melania has been found to embrace such avast number 
of species in various parts of the globe, that it has become very de¬ 
sirable to separate any definite group with sufficient persistent cha¬ 
racteristics. The thickened lip sufficiently distinguishes the proposed 
genus from Melanopsis and Melania J. It differs from Melanopsis 
also in its having no sinus, while it resembles it in the possession of 
a thickened columella above. From Melania it differs also in having 
this callous columella. The species on which it is proposed to found 
this genus has a mouth looking like a thick-lipped Bulimus. The 
operculum differs somewhat from that of any Melanian I have seen. 
Its polar point is subcentral, from which two or three spiral revolu¬ 
tions are made ; then a thinner margin surrounds these spirals. 
The animal has not been observed, and may and probably will 
prove very different from Melania. Its proper position, however, in 
the system will most likely be found to be between Melanopsis and 
Melania, and there I would at present place it. 
A second and very distinct species may be added to this genus— 
the Melania Icevissima, Sowerhy, described in Deshayes’ edition of 
Lamarck. It inhabits Colombia, and is a shorter, wider, and much 
thicker shell, with a large white mouth. 
Pachyxhilus Cumingii. P. testd Icevi, elevaio-conicd, sub - 
crassd, nitidd,fusco-nebulosd; spird elevatd, acuminata; anfrac- 
tibus unclecim, convexiusculis; suturis linearibus; apertura par- 
viusculd, subrotunda, ad basim rotundd, intus fused; labro valde 
expanso ; columella superne incrassata. 
Hab. Large rivers. Copan, Central America. 
Length T4, diam. ’5 of an inch. 
Remarks .—This is a very remarkable shell among the Melaniens. 
It is of fine symmetry, the whorls being very regular to the apex. 
The brownish cloudiness gives the whole surface a dark hue, while 
the smoothness of the whorls gives it almost a polished appearance. 
It differs very much in form from Melania Icevissima, Sow., which 
naturally belongs to the same genus, and which is adopted above ; 
but it has the same character of mouth and exterior colour. Both 
* All the species described are in the Cabinets of Hugh Cuming and Isaac Lea. 
f thick, and xeiXos, lip. 
+ Lamarck describes the family Melaniens as having a sharp outer lip, “ le 
droit toujours tranchant; ” but this genus naturally belongs to Melania, Mela¬ 
nopsis, and Pirena. 
