362 MAZATLAN UNIVALVES 



419. Jeffeeysia* bifasciata, n. s. 



J. t. suhelevatd, diaphand, tenuissimd, Icevi, anfr. v. subtumi- 



dis, sutura impressd ; lined spirali subsuturali ; anfr. prima 



minutissime granulato ; pallide fused, fasciis .spiralibus duabus 



fiiscis ornatd ; aperturd siibovali, peritremati contintu), umbilico 



minimo ; operculo rufesceyitc, liaud tenuissimo. 



Variat t.phcs minusve elongatd ; colore quoque pallida s»u corneo. 



Of this species, beautifully lustrous when viewed under the 

 microscope with a good light, about 90 specimens were obtained, 

 probably from the Alga; on the Uvanillaj. They are most likely 

 of somewhat sedentary habits, as even in a living state they 

 are not unfrequently incrusted with Coralline. The dried 

 animals have a rich brown colour. Several retained their 

 opercula, which are perfectly normal, and of a reddish brown. 

 Long. "055, long. spir. '032, lai. "03, div. 30°. 

 JIab. — Mazatlan ; rare, on PAlga;; L'pool Col. 



Tablet 1716 contains 3 sp. richly coloured, of which 2 retain 

 their opercula. — 1717, 3 sp. pale non-banded variety, one with 

 beautiful incrustation of Coralline. 



420. PJeffeeysia Aldebi, n. s. ' 



J. t. "J. bifasciata;" simili, sed soUdiore, multo tnoQore ; anfr. 

 V. magis planatis, fasciis angustis. 



Thi-ee dead specimens were found on Chamrc which appear 

 to be a distinct species. Of the very numerous specimens of 

 J. bifasciata, none approached it in size, though the number 

 of whirls is the same. The station appears to be different, 

 and the whirls flatter. It is dedicated to one who stands 

 unsurpassed for accuracy and courtesy among British Malaco- 

 logists, and to whom we owe the first full description of this 

 very interesting genus. Long. '068, long. spir. '035, lat. 'OiA, 

 div. 35°. 

 TZai.— Mazatlan ; extremely rare, on Chama ; L'pool Col. 



Tablet 1718 contains the least incrusted specimen. 



• As a name, Rissoella has precedencp ; but as the first aecnrate account of the 

 genus was given by Alder, il seems fair to adont his designation ; especially a» 

 Itissoid names are suftlciontly plentiful, and tne other is at the same time dis- 

 tinctive, and preserves the remembrance of one of the most accurate labourers 

 in British Malacology. I'hilippi has settled the difficulty by adopting both 

 names as separate genera, of which ho places Jeffreysia in Paluoinidse and 

 Kissoella in Eulimidas. 



