OF MOLLUSCA. 33 



b. Animal oviparous ; nucleus of shell regularly spiral. Foot 

 moderate. 



* Mantle enclosed; inner lip of shell defined, not expanded ; pillar 

 with five or six strong sub equal plaits. Operculum none. 



2. Cymbium. 

 Shell ventricose, covered with a homy periostraca ; spire short, 

 depressed, often imbricated ; mouth very large, expanded . 



§ Spire hidden. 



1. C. melo. 



§§ Spire conic, hooded with spines; spines bent down towards tip. 



2. C. nauticum. 



3. C. £ethiopicum, t. 25. f. 1 ; Adams, Gen. Moll. t. 17. f. 4. Shell 



brown. 



4. C. Miltonis. Shell white and brown marbled. 



§§§ Spire conic ; spines large, produced. 



5. C. ? Spines subequal, in adult state wanting. 



6. C. armatum, t. 264. f. 1, t. 265. f. 1 . Spines becoming larger and 



much produced, and increasing with age. 



§§§§ Spire large ; spines small, numerous, subbiflexed. 



7. C. Broderipii=C. Regius. 



3. SCAPHA. 



Shell ovate or fusiform ; periostraca smooth, thin ; spire conic ; 

 mouth moderate ; inner lip even. Operculum none. 



§ Nucleus smooth. 



1. S. colocynthis, t. 27*. f. 2; Adams, Gen. Moll. t. 18. f. 1. 



2. S. pacifica, t. 27. f. 3, t. 263. f. 1. 



3. S. fusus, t. 27. f. 2 ; Adams, Gen. Moll. t. 18. f. 3. 



§§ Nucleus moderate, crenulated. 

 1. S. vespertilio, t. 26. f. 1, 2, 3 ; Adams, Gen. Moll. t. 18. f. 2. 



Mantle of Scapha vespertilio free for half an inch on pillar side ; 

 siphon elongate, produced, conical, with conical tentacular auricles 

 on the sides of the base ; penis elongate, conical, bent back, com- 

 pressed ; tentacles lateral, subulate, far apart at the base, and united 

 by a broad veil fringed on the edge ; lingual membrane elongate, 

 narrow. Teeth in a single series, with three teeth in front, the 

 central largest ; hinder edge lunate. 



