252 MAZATLAN UNIVALVES 



which covers the umbilicus, leaving only a slight chink. A 

 second sp. agrees in all respects except that the spiral sculp- 

 ture is coarse and somewhat moniliform ; but it is too much 

 weathered to decide on its affinities with confidence. Long. '019, 

 lat. '039 by '034, div. 153. 



Sab. Mazatlan ; 2 sp. off Chama and Spondylus ; L'pool Col. 

 Tablet 1170 contains the typical specimen. 



320. ETHALIA PALLIDULA, n. s. 



H. t. globosd, solidd, alba ; ad spiram planatd, ad basim pro- 

 ductd ; anfractibus iii., suturd indistinct d, apice planatd ; tot a 

 superficie striis spiralibus subrugulosis impressd ; callositate 

 minima ; umbilico nullo ; aperturd elongatd, ad basim sub- 

 angulatd ; labro acutiore, labio conspicuo. 



A. little globular shell, produced at the base of the columella, 

 and presenting the general aspect of the young of Lacuna 

 pallidula. It is on the extreme verge of the genus, the com- 

 pact spire preventing the development of the callus. Long. '029, 

 lat. '044 by '035, div. 170. 

 Sab. Mazatlan ; 1 sp. off Spondylus ; L'pool Col. 



Tablet 1171 contains the specimen. 



321. ETHALIA CABIN AT A, n. s. 



E. t. discoidali, planatd, aurantio-fuscd ; anfractibus iv. et 

 dimidio, quarum iii. primi Iceves, vix amplectentibus, suturd 

 valde impressd ; sub peripheriam acute carinatd ; totd super- 

 ficie rugulis incrementi confertissimis ornatd ; regions umbilicali 

 concavd ; callositate spirali elongatd, angustd, rimam conspicu- 

 am umbilicalem gyrante,juxta labium p arum planatd ; aperturd 

 subquadratd, sinuatd, a carind angulatd ; labio ad parietem 

 nullo ; labro intus suturam parum calloso. 



This charming little shell has the general aspect of Planorbis 

 carinatus, but with the whirls a very little elevated, and the 

 keel just below the centre. The whirls very slightly embrace, 

 but are cemented by the long, thin callus. Both above and 

 below, it is covered with extremely close, rugulous, radiating 

 striulse. In its mode of growth it affords a transition to Teino- 

 stoma. Long. 013, lat. '038 by '033, div. 175. 

 Sab. Mazatlan ; 2 sp. off Spondylus ; Lpool Col. 



Tablet 1172 contains the freshest (but smallest) specimen. 



