;^;^6 SMITH : nomenclature of certain genera. 



the name, calling it Bidlinus, was right in assigning its origin to 

 the latin Bulla (a bubble), for Adanson states that he used 

 the name Bulinus because " sa coquille flotte comme une 

 petite bulk d'air transparente." 



PALUDESTRINA vice HYDROBIA. 



The genus Hydrohia was indicated, but not described, by 

 Hartmann in 1821,^ but as this term was preoccupied by 

 Leach for a genus of Coleoptera {Hydrobius), it becomes 

 necessary to employ some other name for this group of 

 molluscs. In his treatise on the Hydrobiince Stimpson" ex- 

 presses the opinion that the two names are " sufficiently distinct 

 to avoid confusion" and Jeffreys-' makes some observations to 

 the same effect. Personally I fully agree wiih this view, but as 

 the laws on nomenclature set forth by the British Association 

 which are almost universally accepted, forbid the employment 

 of the same generic name in more than one branch of zoology, 

 the term Hydrobia (merely the feminine ioKm.oi Hydrobius) can 

 no longer be used in conchology. For this reason it was cast 

 aside by Moquin-Tandon"*. 



Paludestrina was founded by D'Orbigny in 1840^ as a 

 subgenus of Paludina, and he selected P. acuta ( Drap. ) as his 

 type. He subsequently'' raised it to generic rank but gave 

 no additional details or reasons for so doing. It is a curious 

 coincidence that the first species quoted by Hartmann, and 

 which therefore may be regarded as the type of his genus 

 Hydrobia^ should be the same as that chosen by D'Orbigny. 



Some of the species described by the latter author may 

 not belong to Paludestrina ; for instance, P. peiistouiata and 

 P. lapidum have a very Lilhoglyphus-Yike. appearance. This, 

 however, will not affect the employment of this generic term, 



1 Sturm's Deulschlands Fauna, vi. (5) pp. 47, 58. 



2 Smithsonian Reports, 201, p. 6. 



3 Brit. Conch, vol. i, p. 64. 



4 Hist. Nat. Moll. France, vol. ii, p. 515. 



5 Voy. Am^r. M^rid., Mollusques, p. 381. 



6 Sagra's Hist. Cuba, Mollus (1841) vol. ii. p. 7. 



J.C, vi., Apr,, 1S91, 



