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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 HuGcu Cumine, Ese., puRING HIS 
ZOOLOGICAL VOYAGE IN THE EAST, AND NOW FIRST DE- 
SCRIBED. By Isaac Lea anp Henry C. Lea, Puiwa- 
DELPHIA *. 
Genus PacHycuILus f. 
Testa conica. Apertura ovata, basi integro. Labrum crassum. 
Columella superné incrassata. Operculum suborbiculare, corneum. 
The genus Melania has been found to embrace such a vast 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 Melaniat. 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 moMewtiat 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 levissima, Sowerby, described in Deshayes’ edition of 
Lamarck. It inhabits Colombia, and is a shorter, wider, and much 
thicker shell, with a large white mouth. 
Pacuycuitus Cuminer. P. testd levi, elevato-conicd, sub- 
crassd, nitidd, fusco-nebulosd ; spird elevatd, acuminatd ; anfrac- 
tibus undecim, convexiusculis ; suturis linearibus ; aperlurd par- 
viusculd, subrotundd, ad basim rotundd, intus fuscd ; labro vaide 
expanso ; columelld superne incrassatd. 
Hab. Large rivers, Copan, Central America. 
Length 1:4, diam. °5 of an inch. 
Remarks.—This is a very remarkable shell among the Mélaniens. 
It is of fine svmmetry, 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 levissima, Sow., which 
naturally belongs,to the same genus, and which is adopted above ; 
but it has the same cs eee of mouth and exterior colour. Both 
4 
* All the species described are in the Cabinets of Hugh Cuming and Isaac Lea. 
+ Tlayds, thick, and xeidos, lip. 
+ Lamarck describes the family Mélaniens as having a sharp outer lip, “le 
droit toujours tranchant ; , but aa genus naturally belongs to Melania, Mela- 
nopsis, and Pirena. 
