cerithiid.t:. 117 



pletely the aspect of a Melaniau that it is very probable Adams was 

 deceived as to his operculum really belonging to it. 



Section Gourmya. Bayle, 1884. 



No internal plications or tubercles ; outer surface smooth. 

 Section Ditretus, Piette, 1874. 



Turreted, with longitudinal rows of tubercles ; outer lip thick- 

 ened, prolonged below so as to close the canal — which is short, 

 inner lip spread out, callous. P. rostellaria, Buv. Jurassic. 



Subgenus Telescopium, Montfort, 1810. 



Shell conical or trochoidal, of numerous flat whoi'ls, the aperture 

 subquadrangular, short, not channeled behind ; lip thin, sinuous, 

 prolonged at the base ; columella interiorly plicate, plication visible 

 near the suture. 



P. telescopium is so abundant near Calcutta as to be used for 

 burning into lime ; great heaps of it being first exposed to the sun, 

 to kill the animals. In Borneo it is an article of food. 



Subgenus Vicaria, d'Archiac, 1854. 



Turreted, spirally striated, Avith a row of tubercles next below 

 the suture ; canal very short, recurved, inner lip callously thick- 

 ened, the callosity prolonged behind, where the aperture is chan- 

 neled ; outer lip strongly sinuated ])osteriorly. 



P. Verneuili, d'Arch. Nummulite, India. 



Subgenus Pirenella, Gray, 1847. 



Shell turriculated, granose, with irregular ribs and varices ; 

 aperture rounded, terminating in a short anterior canal ; inner lip 

 simple, outer lip thin, sinuous. P. mamillatus, Phil. 



Subgenus Cerithidea, Swainson, 1840. 



Turriculated, longitudinally ribbed ; whorls numerous, apex 

 more or less truncated ; aperture rounded, slightly transversely slit 

 anteriorly ; outer lip expanded, thickened, broadly rounded below 

 and usually produced into a beak, crossing the sinus to the left. 

 Eye pedicels long and thick, connate with the tentacles nearly to 

 their tips. 



They are so commonly out of the water as to have been taken lor 

 land shells. P. decollatus, Linn. 



Section Aphanlstylus, Fischer, 1884. 



Shell decollated, thin, last Avhorl cariuated ; lip not dilated, nor 



