OF CONCHOLOQV. 85 



Metamorphosis out of the egg (larva, swirnmirig.) 



c. Marina. (Jerithium, Turritella. 



Metamorphosis within a sac. 



d. Parasitica. Vermetus, flalyptnea, Hipponyx. 



e. Pelagica. lltteropod t . 



B. Prohoscidifera. — Moutli at the extremity of a retractile 

 proboscis. Larva swimming. Natica, Cassis, JJoliuni, 

 Triton, Ranellt. — Proboscis not retractile, Cyprwa, 

 Stromhus. 



II. Rachiglossata. — Lingual teetli disposed in thi'je longitu- 



dinal rows, simph^ sharp, not curved, (^except Voluta, 

 which has but one row.) Mouth at the extremity of a 

 retractile proboscis. Eggs enclosed in corneous cap- 

 sules. [Melicertiqenes.) — Marginella, Vohita, Harpa, 

 Oliva, Nassa, Buccinum, Fasciolaria, Fusus, Mure.r. 

 TurbineUa, Purpura, Columhella, Mitra. 



III. Toxoglossata. — Lingual teeth subulate, Avith an external 



or internal veneniferous canal. Cancellaria, Terebra, 

 Clionella, Pleurotmna , Conue, 



Series IL— DIOCORDIA. 

 Heart triloculai", witli two auricles surrounding the rectum. 



Glass III.^-PSEUDOPHALLIA (ASPIDOBRANGHI A, Ohm.) 



Sexes separate, but without external male organ. The 

 question of copulation in this class, or the mere dispersion of 

 semen, as with the Acephala, is undetermined. The heart is 

 provided with two auricles, even with the genera which have 

 not more than a single branchia. (See "Voyage of the Jstro- 

 /aiie," Anatomy of Turbo marmoratus.) Development known 

 only in Chiton and DeMalium. 



I. RJii'pidoglossata. — Lingual teeth numerous, disposed in tw/) 

 orders, the marginal ones aciculate and turned into 

 hooks. 



a. Terrestria, Helicina. 

 h. Fluviatilia. Neritina. 

 c. Marina. Nerita. 



Trochoidea, {Haliotis.) 

 Fissurellidea. 



