GUPPy : MOLLUSCA. OF TRINIDAD. 227 



I am in doubt again as to the validity of this name. I let 

 it stand for the present, however, but add two more species of 

 the genus which I have found since my last list was printed. 



48. Truncatella bilabiata Pfeiff. 



I should be inclined to add to the synonymy of this species 

 the names of barbadcnsis Pfeiff. and modesta Adams. It is very 

 nearly allied to, and perhaps not really distinct from, Tr. 

 pnhhella. 



49. Truncatella subcylindrica Gray. 



This is near to and possibly identical with Tr. caribalensis 

 Sow. 



It is singular that this and the preceding live together side 

 by side, being most abundantly found in sheltered bays at the 

 extreme top of highwater mark. It is unusual for two allied 

 species to be found living on the same ground, except under 

 particular circumstances. What, in this instance, is the par- 

 ticular circumstance which determines the association of two 

 clearly distinct though allied forms I am unable to state. Can 

 it be sexual ? ' 



50. Taheitia reclusa Guppy. 

 Blandiella reclusa 'Amer. Journ. Conch.,' 1870, p. 309, pi. xvii., 



f. 7-8. 

 Crosse, 'Journ. de Conch.,' 1890, p. 56, No. 53, pi. ii., f 7. 



This mollusca is allied on one hand to Triincatella and on 

 the other to Geomelania. From the latter it differs in the 

 absence of the linguiform appendix of the labrum and in the 

 rugose operculum. 



51. Cistula aripensls Guppy. 



Crosse, I.e., p. 56, No. 52, pi. ii., i. 6. 



An oblong-turreted longitudinally costellate-striate shell, 

 of a reddish-brown color, generally with several more or less 

 interrupted dark spiral bands and an oval aperture, with an 



