BY E. M. JOHNSTON, F.L.S. 



103 



(Ixvii.) Family Siphonaeiid^i. 

 Genus Siphonaeia. (560-562.) 



Shell solid, porcellanous ; apex central or sub-central ; 

 provided with more or less elevated radiating ribs or 

 ridges, which by their projection render the margin 

 irregular. Dist.— Cape, India, Philippines, Australia, 

 New Zealand, Pacific, Gralapagos, Peru, Cape Horn, 

 West Indies, West Coast of North America. 



Class SCAPHOPODA. 

 (lxviii.) Family Dentaliil\s). 

 Genus Dentalitjm. (563-564.) 

 Shell tube-like, gradually tapering posteriorly, longtitudinally 

 ribbed, margin of the aperture sharpened, posterior end 

 with an internal, slightly projecting tube, which is 

 provided with a dorso-ventrally elongated opening ; 

 the outer layer having a very slight emargination 

 dorsally and ventrally. Dist. — Universal. 



Class PELECYPODA. 

 (Lamellibranchiata. Conchifera. ) 

 (lxixj Family Gastbociminid.e. 

 Shell equivalve, gaping ; valves thin, edentulous, united by a 

 thin external ligament, sometimes cemented to a shelly 

 tube when adult ; adductor impressions 2, pallial line 

 sinuated. 



Genus Aspeegillum. (565.) 

 Shell small, equilateral, cemented to the lower end of a shelly 

 tube, the umbones alone visible externally; tube elongated, 

 closed below by a perforated disc, with a minute 

 central fissure ; siphonal end plain, or ornamented 

 with ruffles. Dist. — Bed Sea, Java, Australia, New 

 Zealand ; in sand. 



Genus Gasteocieena. (566.) 

 elongated, narrow, contained within a shelly tube ; 

 posterior adductor nearly central, with a pedal star in 

 front ; siphonal inflection angular, with its apex joining 

 the pallial line ; tube round, straight, tapering 

 upwards, transversely striated, closed at the lower end 

 when complete, and furnished with a perforated 

 diaphragm behind the valves. Dist. — Madagascar, 

 India, Philippines, Australia ; burrowing in sand or 

 mud. 



Shell 



