136 



CONCHOLOGY. 



minates the shell ; an operculum. This genus is distinguished 

 from the Strombus by having a sinus in the lower part of the right 

 margin contiguous to the canal. Inhabits the European seas 

 four living species. Three fossil. 



Rostellaria curvirostris. Rostellaria pespeHcani. 



R. rectirostris. K. cancellata. 



2. Genus Pteroceras. PI. XII. 

 .Animal. See Strombus, below. 



SJielL Oblong-ovate ; canal elongated, attenuated and often 

 closed ; right margin dilating by age into an expanded digitated 

 wing, attached to and covering a short spire with a sinus in the 

 lower part not contiguous to the body. Distinguished from the 

 Strombus by not having the canal at the base shortened or trun- 

 cated, and from the Rostellaria by having the sinus of the right 

 margin distant from the body. Found in the Equatorial seas. 

 Seven species. Five fossil. 



Pteroceras truncata. Pteroceras chiragra. 



P. lambio. P. millepeda. 



P. Scorpio. P. pseudoscorpia. 



P. aurantia. 



3. Genus Strombus. PI. XII. 



.Animal. Spiral ; the foot rather wide anteriorly, compressed 

 posteriorly ; mantle thin, forming a prolonged fold anteriorly, 

 whence issues a sort of canal ; head very distinct ; mouth a ver- 

 tical slit at the extremity of a proboscis, piovided in the inferior 

 median line with a lingual band having prickles flexed posteri- 

 orly ; tentacular appendages cylindrical, thick, and long, with the 

 eyes at their extremity. 



Shell. Thick, subinvolute, dilated in the middle, terminating 

 in a cone anteriorly and posteriorly ; aperture very long and 

 narrow ; terminated anteriorly by a canal more or less elongated 

 and flexed ; edges parallel, the external dilating with age, pre- 

 senting posteriorly a gutter at its point of attachment with the 

 spire, and, anteriorly, a sinus behind the canal, through which 

 the head of the animal passes ; operculum horny, long, and 



