1836.] Description of a new Genus of MoIIusca. 781 



neck, more or less blotched with blue ; rump, immaculate : bill, 

 black : iris, dull brown : legs, fleshy-grey : sexes exactly alike : struc- 

 ture typical : tail long and deeply forked : size of H. Rustica. 



Remark. This is the common Swallow of the central region, a 

 household creature remaining with us for seven or eigbt months of 

 the year. 



Species 2nd. Rupicola, nobis. 



Earthy grey brown : below, from the chin to the vent (exclusively), 

 rufescent white : legs fleshy grey : bill black : iris brown : sexes 

 alike : larger than the last, 6f by 14| inches, and weight 1^ oz. : 

 structure typical : wings exceeding the short and subfurcate tail. 

 Habitat, the central and northern regions : not migratory : adheres to 

 the mountains, preferring rocky situations. 



N. B. The remaining Hirundine birds of Nepal are Hirundo Rus- 

 tica and the Sand-Martin ; both of which, but especially the latter, 

 are common. 



IV. — Description of the Shell and Animal of Nematura, a new Genus 

 of Mollusca, inhabiting situations subject to alternations of fresh and 

 brackish water. By W. H. Benson, Esq. B. C. S. 



Animal. — Caput tentaculis duobus setaceis oculis postice prope bases 

 tentaculorum sessilibus ; proboscide elongata, cylindracea, extensili. 



Pes ovato-oblongus, medio ventricosus, postice angustatus, acumi- 

 natus, processu brevi filiformi subito desinens ; antice expansus, medio 

 profunde emarginatus ; ala utroque latere porrecta late angustata, 

 acuminata. 



Testa ovata, ventricosa, a latere compressa, ultimo anfractu insuper 

 aperturam angulato, deflexo. Apertura, integra, constricta, orbiculari, 

 supra vix angulata. ; peritremate acuto leviter intus incrassato. Oper- 

 culo tenui in spiram planam convoluto. 



The snout is capable of great extension, and the animal is able to 

 lick the summit of the shell with its extremity, which is armed with- 

 in the mouth with a pair of strong vertical jaws, each apparently 

 consisting of two pieces : these are constantly in motion in a verti- 

 cal direction. The centre of the foot has a rounded peltate appear- 

 ance, occasioned by the adaptation of its form to that of the opercu- 

 lum, which is visible through the transparent foot when viewed on 

 the under side. The singular short filiform process attached to the 

 extremity of the foot appears to be the termination of a nerve or 

 minute canal, which is seen extending directly up the centre of the 

 foot until it is lost under the operculum. The excrement is voided 

 from the right side of the animal. 



