PTEROPODA. 141 



lal^ro subquadrato. — Dorsal disc longitudinally trilobate ; two 

 spines on the rounded apex, similar to the usual lateral 

 appendages, making, as it were, a four-toothed termination. 



10. OBTUSA, f. 13, Sowerby. —Fallide succinea, tenuissime 

 hyalina tumida ; apice subtruncato, vix bideutato ; appendi- 

 cibus bidentatis ; labro subanguste producto. — The side ap- 

 pendages and obtuse apex have each two very small spines. 



11. LiMBATA, f. 14, 15, Orhif/ny.—'Piillide lilacina vel suc- 

 cinea, trigona ; disco ventrali tumido ; rostro elongato, infra 

 medium leviter contracto, ad terminum acute biangulato, 

 appendicibus alatis acuto bispinosis ; apice obtuse bidentato. 

 — The rostrum is lengthened, slightly contracted below the 

 middle and separated into two sharp points at the end ; the 

 appendages are wing-like and double pointed, and the apex 

 has two very tine points. 



12. LONGiROSTKis, f. 16, LesuGuv.—FL limhatcB similis, sed 

 rostro infra medium acute contracto. — Differing from sp. 11 

 in the sharp contraction of the rostrum, at the end of the 

 lower disc. 



13. MiNUTA, f. 19, Soiverhy. — Minuta, cffsruleo-alba sub- 

 quidi-ata oblonga ; appendicibus minutis ; apice minutissime 

 bidentato ; apertura semilunari angusta ; rostro nullo. 



14. INTERMEDIA, f. 11, Soivevhy. — Quam H. intermedia 

 brevior, appendicibus magis distantibus et productis ; apice 

 magis producto et dentato. — Similar to sp. 13, but with 

 the spines on the apex and the lateral appendages more 

 developed. 



Sub-genus Diacria. 



15. LABiATA,f. 23, 24, Oblrjny.—Alha elongata subtrigona ; 

 apertura lilabiata ; rostro producto ; appendicibus lateralibus 

 elatis, distantibus, acute productis; apice longe producto, 

 retrorsim uncinate. — Having all the parts of the typical 

 Hyalasa?, but in form and proportions leading to the sub- 

 generic form Didcria. 



IG. TRispiNOSA, f. 20, Lesueur. — Alba, part im fusco irregu- 

 lariter suffusa, quadrilateralis, compressa; disco ventrali pla- 

 niusculo ; disco dorsali trilobate, concentrice rugato ; appendi- 

 cibus magnis spinitbrmibus rcctis, apertura angusto ; labro 



