58 MALACOZOA. GASTEEOrODA. PECTINIBRANCHIaTA. 



opaque, of five rounded turns reticulated with longitu- 

 dinal and transverse slender ridges, the aperture roundish, 

 the outer lip tliickened externally. Reticuldtus, covered 

 with net-work. 



9. R'lssoa Pulhis. — Shell ovate, of five httle convex, 

 glossy turns, the last as long as the spire, and banded 

 with red ; the aperture roundish-ovate. PiiUus, a 

 chicken, or any young animal. 



10. Rissoa tristridta. — Shell ovate, of five convex, 

 glossy turns, having three impressed lines along their 

 upper margin, the last with three rows of rhomboidal 

 red spots; the aperture roundish. Tristridtus, 'v\ith 

 three strise. 



11. Rksoa trnncdta. — Shell oblong, subcylindrical, 

 abruptly obtuse, of five turns, separated by a distinct 

 suture, and transversely striato-sulcate ; the aperture 

 ovate. Truncdtus, abruptly terminated. 



12. Rissoa stridta. — Shell oblongo-turrite, subcylin- 

 drical, opaque, of six rounded, spirally striate turns, with 

 obsolete ribs at their upper margin ; the outer hp pro- 

 jecting and considerably thickened. StridtuSj striated, 

 scored with lines. 



13. Rissoa grdcilis. — Shell turrite, subcylindrical, thin, 

 pellucid, glossy, of six turns, the aperture ovate, little 

 narrowed behind, the outer lip thickened. Gracilis^ 

 slender. 



Family IV. — Tornatellina. 



Shell spiral, ovate, oblong, or turrite, with the aperture 

 oblique, ovate, oblong, or narrow, entire anteriorly, nar- 

 rowed behind by the convexity of the last turn, the inner 

 lip ending in an obUque plait on the columella. Named 

 from the genus Tornatella. 



Genus I. Odostomia. — Shell ovato-conical, with the 

 apex rather obtuse or mammillate, the aperture suboval, 

 the peristome incomplete behind, and having a tooth- 

 like plait. 'oSovy, tooth ; ord/za, moutli. Fleming. 



1. Odostdmia unidentdta. — Shell ovate, of four or five 

 moderately convex, glossy turns, the last veutricose, 



