428 



19. C.ECUM QUADRATUM, Cpi\ 



C. (Anellutn) t. parva, curta, solida, annulis quadratis xii.-xx. 

 cincta, interstitiis profundis, quadratis ; apertura subcontracta, 

 annulis concurrentibus ; septo mucronato ; mucrone parvo, ex- 

 tante, angusto, subdextrorsum sito ; margine laterali concavo : 

 operculo valde concavo, anfr. circ. x., linea spirali expressa. 



? Var. compactum. T. interstitiis parvis seu evanidis, annulis 



tnaxime planatis. 

 Long. -072, lat. (interst.) -016, (annulis) -02. 

 Hab. Mazatlan, rare. Mus. Brit. &c. 

 Maz. Cat. p. 322. 



The extreme forms are very different ; but no uniform character 

 has been observed by which they can be separated. 



20. CAECUM CLATHRATUM, Cpr. 



C. (Anellum) t. haud parva, solidiore, annulis valde distantibus, 

 acutioribus, extantibus cincta ; interstitiis concavis ; septo sub- 

 planato, mucronato; mucrone minima, obtuso, pcene in dorsum 

 sito ; margine laterali in adulto haud conspicuo, planato : 

 operculo ? . . . 



Test. jun. long. -057, lat. 007— 017. 



Test, adult, long. -102, lat. (interst.) -026, (annul.) '03. 



Hab. Mazatlan, very rare. Mus. Brit. &c. 



Maz. Cat. p. 322. 



An extremely beautiful species, remarkable for its size, nearly flat 

 plug, and distant rings with curved interspaces. 



21. Caecum Floridantjm, Stimps. 



C. (Anellum) " t. valde arcuata, solida, alba, nitida ; annulis 

 circa xxxii. acutis, elevatis cincta, interstitiis midto latioribus ; 

 apertura parum obliqua, haud contracta ; interdum annulo lato 

 aperturam superante ; " septo ?....: operculo ? 



Long. -075, lat. -02, poll. 



Hab. Florida. 



Stimpson in Proc. Bost. Soc. Nat. Hist., Oct. 15th, 1851. 



22. CiECUM REGULARE, 11. S. 



C (Anellum) t. satis tereti, tenuiore, alba, subdiaphana ; annulis 

 subacutis, regularibus xx.-xxiv. cincta, interstitiis conspicuis ; 

 apertura declivi, contracta, haud incrassata ; septo mucronato, 

 mucrone parvo, haud conspicuo, subdextrorsum sito ; margine 

 laterali parum elevato, subconvexo : operculo 1 



Test. jun. long. -04, lat. -007— -014. 



Test, adult, long. -085, lat. '018— -024. 



Hab. W. Indies (Woodward) ; Singapore, 2 spec, from Litho- 

 phagus burrow in Plicatula ; Australia, 1 young sp. in Petalocon- 

 chus nerinceoides. Mus. Brit. &c. 



Twelve specimens of this species have been examined from the W. 



