68 MALACOZOA. GASTEROPODA. TECTIBRANCHIATA. 



and convolute, or none. Named from one of the genera, 

 BidlcBa, 



Genus 1. Bull^a. — Shell in the substance of the 

 mantle, over the branchise, very thin, partially curved 

 in a spiral form, but without spire or columella, the 

 aperture very wide, and extending the whole length of 

 the shell. Bulla, a bubble. 



1. BullcBa punctuldta. — Shell broadly ovato-elhptical^ 

 transparent, glossy, with numerous longitudinal striae, 

 and transverse raised lines, leaving between them regu- 

 lar series of squarish depressions. Punctuldtus, marked 

 with little dots. 



2. BuUcea Catena. — Shell oval, transparent, glossy, 

 subtruncate at the upper end, rounded at the other, the 

 surface with regular distinct divergent, catenulate striae. 

 Catena, a chain. 



3. BullcBa catenidifera. — Shell oblongo-cylindrical, 

 transparent, glossy, truncate at the upper end, wider and 

 rounded at the other, the surface with regular distinct 

 divergent catenulate striae. Catenula, a little chain ; 



ferOi to bear. 



Genus 2. Bulla. — Shell partly external, very thin, 

 involute, with the aperture extending its whole length, 

 oblongo-linear, wider below. Bulla, a bubble. 



1. Bulla Crdnchii. — Shell ovato-elliptical, subtrun- 

 cate, with a small spiral pit, the surface somewhat glossy, 

 longitudinally divergingly striate, about ten striae at the 

 upper and eighteen at the lower end large, all punctate. 

 Named after Mr. Cranch. 



2. Bulla Candida. — Shell broadly ovate, semitranspa- 

 rent, glossy, with faint growth-lines, the apex prominu- 

 lous, obtuse, but with a shght scrobiculus, the aperture 

 ovato-oblong. Cdndidus, white. 



Genus 3. Halia. — Shell obovate ; the last turn very 

 large, ventricose ; the spire prominent, convex, obtuse ; 

 the aperture ovato-trigonal, curved anteriorly to the left. 

 Name that of one of the Nereids. Risso. 



