FAMILY 3. CYCLOSTOMACEA. el 
is expanded and reflected, and sometimes ornamented with a frill. The 
operculum is either horny or calcareous, and always spiral. 
The Cyclostomata are exceedingly numerous in species ; they live for 
the most part in the vicinity of lakes or rivers, and are more or less dis- 
tributed throughout the globe; the more beautiful varieties of form or 
colour abounding in warm and tropical regions *. 
Examples. 
Pl. CLXXXIII. Fig. 1. 
CycLOSTOMA SEMILABRUM, Lamarck, Anim. sans vert., new edit., vol. viii. 
p. 357. Delessert, Recueil de Coquilles, pl. 29. f. lL. a, b. 
Pl, CLXXXIIL. Fig. 2. 
CycLostoma nitipuM, Sowerby, Proceedings Zool. Soc., 1842. 
Pl. CLXXXIII. Fig. 3. 
CycLostoma GoNIostoma, Sowerby, Proceedings Zool. Soc., 1842. 
Pl. CLXXXIII.. Fig. 4.: 
CycLostoMa opsoLetum, Lamarck, Anim. sans vert., new edit., vol. vii. 
p.- 355. Delessert, Recueil de Coquilles, pl. 29. f. 11. a, b,c. 
Pl. CLXXXIII. Fig. 5. 
CycLosTOMA FIMBRIATULUM, Sowerby, Appendix to Tankerville Cata- 
logue, p. vill.; Species Conchyliorum, Part 2. f. 136. 
Pl. CLXXXIII. Fig. 6. 
CycLostoma STarINnForTHII, Sowerby, Proceedings Zool. Soc., 1842. 
* Mr. Sowerby has kindly permitted us to refer to his figures of Cyclostomata in Part 2. 
of the ‘Species Conchyliorum,’ which we are happy to announce is now nearly ready for 
publication. The beautifully illustrated monograph of this genus, upon which he has been so 
long employed, will certainly be a most elaborate contribution to our catalogue of species. 
VOL. II. 10) 
