422 



rail concavo : operculo valde concavo, anfr. aire. xii. ; lira pro- 



minente spirali, marginem quasi duplicante. 

 Test. jun. long. -047, lat. -017. 

 Test, adult, long. -14, lat. -02— -032. 



Var. tenuiliratum : t. liris crebris, tenuibus ; apice parum pro- 

 minent e. 



Var. subobsoletum : t. alba, alabastro simili ; liris paucis inter- 

 dum vix monstrantibus . 



1 Var. subconicum : t. septo maxime elevato, subconico. 



Hab. Mazatlan, rare. Mus. Brit. [? Singapore, 1 sp. Mus. 

 Brit.] 



Maz. Cat. p. 317. 



Although about seventy specimens were found of this species (the 

 least uncommon of the Elephantula), I cannot fix definitely the limits 

 of the species, and one or more of the above varieties may prove 

 distinct. The principal feature is the appearance of rings under the 

 ribs. 



A terminal fragment of an Elephantulum, picked out of mud in 

 the burrow of a Lithophagus in an E. Indian Plicatula received from 

 Singapore, presents no characters by which it can be separated from 

 this species. Perfect specimens will, however, probably prove it to 

 be distinct. 



9. CiECUM HEPTAGONUM, Cpr. 



C. {Elephantulum) t. septangulata ; annulis rotundatis confertis 

 cincta, angulos longitudinales supracurrentibus ; apertura pla- 

 nata, extus heptagonis forma, intus eirculari, sidco concentrico 

 ornata : septo ?....: operculo ? . . . 



Lat. -02. 



Hab. Mazatlan. Mus. Brit. 



Maz. Cat. p. 319. 



Only a mouth -piece was found of this very remarkable species. 



10. CAECUM IMBRICATUM, n. S. 



C. (? Elephantulum) t. haud parva, tereti ; primum leevi ; dein 

 longitudinaliter multangulata, sulcis creberrimis, angustis con- 

 centrice quasi annulata ; adulta, liris longitudinalibus obtusis, 

 angulatis viii.-xiv. polygonata, a sulcis concentricis xxv.— 1. ut 

 in adolescente interrupta ; apertura stellata ; septo subungu- 

 lato, submucronato, plerumque valde prominente ; margine late- 

 rali subconcavo ; apice extante, latiore, marginibus dextrali et 

 sinistro declivibus : operculo 1 . . . . 



Test. jun. long. -06, lat. -008— -014. 



Test. adol. long. -087, lat. -012— "023. 



Test, adultse long. -11, lat. -017— '027. 



Hab. Sponge, W. Indies. Mus. Brit. &c. 



This^extremely beautiful species (like C. heptagonum) is exactly 

 intermediate between Elephanhdum and Anellum. The sculpture 



