1-42 MANUAL OF THE MOLLUSCA. 



They are mostly confined to the fresh waters of warm regions. One sp. (N. 

 tluviatilis) is found in Brit, rivers, and in the brackish water of the Baltic. 

 Another extends its range into the brackish waters of the N. American rivers. 

 And the West Indian N. vlridis and meleagri^, are found in the sea. 



1:^. crepidularia has a continuous peristome, and approaches navicella in 

 form ; it is found in the brackish waters of India. N. corona (^ladagascar) 

 is ornamented with a series of long tubular spines. 



Dlsfr., 76 sp. W. Indies, Norway, Brit., Black Sea, Caspian, India, 

 Philippines, Pacific, W. America. 



Foss'd, 20 sp. Eocene — . Brit., France. &c. 



Navicella, Lam. 



Eti/7n., navicella, 2i smvi^ihodii. 7J//?^, N. porcellana. PL IX., fig. 41. 



Shell oblong, smooth, limpet-like ; with a posterior, sub-marginal apex ; 

 aperture as large as the shell, with a small columeUar shelf, and elongated 

 lateral muscular scars ; operculum very smaU, shelly. 



Distr., 18 sp. India, Mamitius, Moluccas, Australia, Pacific. 



FAMILY IX., TuEBiNii)^. 



Shell spiral, turbinated or pyramidal, nacreous inside ; operculum calca- 

 rious and pauci -spiral, or horny and multi-spiral. ■ 



Animal with a short muzzle ; ej'es pedunculated at the outer bases of the 

 long and slender tentacles ; head and sides ornamented A\ith fringed lobes and i 

 tentacular filaments {cirri) ; branchial plume single ; lingual ribbon long and i 

 linear, chiefly contained in the visceral cavity ; median teeth broad ; laterals J 

 .5, denticulated; uncini very numerous (sometimes nearly 100), slender, with , 

 hooked points (Fig. 15, A.). 



Marine, feeding on sea-weeds (algce). I 



The shells of nearly all the turbinidse are brilliantly pearly, when the ( 

 epidermis and outer layer of shell are removed ; many of them are used in this j 

 state for ornamental purposes. \ 



Turbo, L. Top-shell. 



I 



1 



il 



Efpn., turbo, a whipping-top. 'I 



Sy7i., batillus, marmorostoma, callopoma, &c. (Gray). 'j 



Type, T. marmoratus. PI. X., fig. 2. 



Shell tm-binated, solid ; whirls convex, often grooved or tuberculated ; 

 aperture large, rounded, slightly produced in front ; operculum shelly and 

 solid, callous outside, and smooth, or variously grooved and mammiUated, 

 internally horny and pauci-spiral. In T. sarrnaticus the exterior of the oper- 

 culum is botryoidal, like some of the tufaceous deposits of petrifying weUs. 



Animal with pectinated head-lobes. 



'^ 



