436 
Eelerodisca heterostropha Flem. Edinb. Journ. 1825. p. 247. 
Spirorbis heterostropha Thorpe Brit. Mar. Conch. p. 10. 
Hab. on oysters and other shells , and marine Algæ, in 
Kingsbridge Bay, Devonsliire (Mtg.), on sheltered situations (Flemg.) 
120. SPIRORBIS MINUTUS MONTG. 
Sh. regular, spiral, and orbicular, with the whirl reversed, taper, 
and transversely wrmkled. (Mtg. Dill.) Very small, dirty white, 
with 2 or 3 lateral volutions, wrinhled transversely : sometimes it has 
a slight longitudinal furrow, on each side, forming a ridge, or carina, 
along the back. Diam. ^ lin. (Mtg.) 
Branchiæ ciliated; a clavate lid, varying in colour from brovon 
to green. (Mtg.) 
Serpxda minuta Mont. Test. brit. p. 505. (ed. Chenu. p. 220. 9.) 
» » Mat. & Rack. Lin. Trans. VIII. p. 246. (ed. 
Chenu. p. 238.) 
» » Turt. Diet. p. 150. 
» » Dill. Cat. p. 1072. 
Spirorbis minutus Flemg Edinb. Ene. VII. p. 68. t. CCV. f. 2. 
Heterodisca minuta Flemg Edinb. Phil. Journ. 1825. p. 247. 
Serpula minuta Brown 111. t. 1. f. 51. 
» » Wood Index t. 38. n. 7. 
» » Thorpe Marine Conch. p. 11. 
Hab. the sea on Corallina officinalis; frequent on the English 
coasts. (Mtg.) On substances exposed directly to the motion of the 
waves. (Flemg.) 
Not easily distinguished from S. heterostropha, except by its 
inferior size, rounded base, and habits. (Mtg.) 
121. SPIRORBIS ZELANDICUS GRAY. 
Sh. rever sea ', ivhirls two or three, rapidly enlarging ; the last 
with three spiral ridges, the middle rib most prominent. (Gray.) 
Spirorbis celamlica Gray Dieffenb. N. Zealand 1843. p. 295- 
Hab. Great Barrier Island, on Patella Hookeri. (Gray.) 
122. SPIRORBIS TRICOSTALIS LAM. 
T. anfractibus subdiscoideis ; coslis tribus rotundatis; apertura 
subrotunda. (Lam.) 
Spirorbis trirostalis Lam. V. 1818. p. 360. n. 3. (éd. 2. p. 614.) 
» » Blv. Diet. se. t. 50. p. 302. 
» ., Chenu 111. conch. p. 3. n. 8. t. 2. f. 8. 
t. 1. f. 5. 
Hab. Port Roi Georges, Nouvelle Hollande. (Lam.) 
