MAZATLAN UNIVALVES 



119. JEFFREYSIA* BIFASCIATA, n. s. 



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

 dis, suturd impressd ; lined spirali subsuturali ; anfr. primo 

 minutissime granulato ; pallide fused, fasciis spiralibus duabus 

 fuscis ornatd ; aperturd subovali, peritremati continue, umbilico 

 minimo ; operculo rufescente, baud tenuissimo. 

 Variat t.plus minusve elongatd / colore quoquepallido sen cornea. 



Of this species, beautifully lustrous when viewed under the 

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

 probably from the Algae on the [Jvanillse. 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, lat. '03, div. 30. 

 Hab. Mazatlan ; rare, on PAlgse ; 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. P JEFFREYSIA ALDERI, n. s. 



J. t. "J. bifasciatce" simili, sed solidiore, mullo ma j ore ; anfr. 

 Y. magis planatis, fasciis angusiis. 



Three dead specimens were found on Chamse 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. 'Q4A, 

 div. 35. 

 Hab. Mazatlan ; extremely rare, on Chama ; L^ool Col. 



Tablet 1718 contains the least incrusted specimen. 



* As a name, Eissoella has precedence ; but as the first accurate account of th 

 genus was ftiven by Alder, it seems fair to adopt his designation ; especially as 

 Kissoid names are sufficiently plentiful, and the other is at the same time dis- 

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

 in British Malacology. Philippi has settled the difficulty by adopting both 

 names as separate genera, of which he places Jcffreysia in Paluainidte and 

 liissoella in Eulimidee. 



