MALACOZOA. GASTEROPODA. PECTINIBRANCHIATA. 59 



longer than the spire, the aperture ovate, with a thick 

 tooth-like plait. Unus, one ; dem, tooth. 



2. Odostdmia plicdta. Shell ovato-oblong, of five or 

 six glossy, transversely plicato-striate turns, which are 

 rather flat, but convex toward the suture, the aperture 

 ovate, with a distinct plait. Plicatus, having a plait. 



3. Odost6mia scaldris. Shell ovato- conical, of five 

 thin, transparent, glossy, faintly striated, moderately 

 convex turns, the suture canaliculate, the aperture ovate, 

 with a prominent plait. Scalaris, like a stair. 



4. Odost6mia interstincta. Shell ovato-conical, of 

 five thin, transparent, glossy, rather flat, finely plicato- 

 costate turns, the aperture ovate, nearly half the whole 

 length, with a very small plait. Inter stinctus. 



5. Odostdmia spir&lis. Shell ovato-conical, of five 

 thin, transparent, glossy, nearly flat, finely ribbed turns, 

 the last spirally striated in its anterior half, the two 

 upper striae deeper and running along the spiral suture. 

 Sjpiralis, spiral, in reference to the lines mentioned. 



6. Odostomiasemicostata. Shell ovato-conical, of five 

 thin, transparent, glossy, rounded turns, marked with 

 obsolete longitudinal striulae, and distant, delicate, trans- 

 verse ribs on the upper half of the last turn, no plait on 

 the columella. Semicostatus, half-ribbed. 



7. Odostomia plicdtula. Shell ovato-conical, of five 

 rather thick, opaque, glossy, flat, finely plicato-striate 

 turns, the last with the plicae ending about the middle, 

 and succeeded by three or four spiral striae, the terminal 

 part plain ; a very slight plait, no umbilicus. Plicatulus, 

 finely plaited. 



8. Odostdmia Mariona. Shell ovato-conical, of five 

 convex, thin, transparent rather glossy turns, finely pli- 

 cate transversely, delicately striated spirally, and having 

 the upper margin in the form of a rib. Named after 

 Miss Marion Macgillivray. 



9. Odostdmia Anna. Shell oblongo-turrite, of five 

 rather thick, opaque, glossy turns, the last convex and 

 proportionally larger, the rest flattened, the aperture ovate, 



