420 



operculo concavo, ienui ; anfr. plurimis, lira tenui spiraliter 



ascendente. 

 Long. test. jun. -05, lat. '007— -01. 



Long. test, adult. -155, lat. -025 — *03 (aperturam versus). 

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

 Maz. Cat. p. 315. 



This is the largest known Caecid, and easily recognized by the 

 shape and the very peculiar plug, the apex of which appears like a 

 minute Vitrinella set sideways on the otherwise flat surface. About 

 twenty specimens were found. 



2. Caecum abnormale, Cpr. 



C. {Elephantulum) t. curtissima, valde arcuata, tenuiore ; liridis 

 tenuissimis circ. xxx., aperturce tumenti super en ntibus ; septo 

 mucronato, prominente ; mucrone obtusiore, omnino dextrorsum 

 sito ; margine laterali (i. e. hac specie dorsali) concavo, rapide 

 ascendente : operculo 1 . . . 



Long. -06, lat. -023. 



Hab. Mazatlan, three sp. Mus. Brit. &c. 



Maz. Cat. p. 316. 



The shells of this species are extremely short, and yet so bent 

 that the plug and the inside can be seen at once, while the apex of 

 the plug is on the extreme right, so that the front view of the shell 

 gives its profile. 



3. Cecum insculptum, Cpr. 



C. { Elephantulum) t. juniore vitrea, adulta solida ; liris validis 

 quadratis et interstitiis profundis ornata ; aperturam versus 

 haud tumente ; septo ungulato, subprominente, apice obtuso, 

 paululum dextrorsum verso, margine laterali subrecto : oper- 

 culo 1 . . . 



Test. jun. long. -053, lat. -013— 017. 



Test, adult, long. -133, lat. -023— -028. 



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



Maz. Cat. p. 315. 



Known by the square ribs with deep interstices, and the ungulate 

 plug. 



4. Caecum laqueatum, C. B. Ad. (diagn. auct.). 



C. {Elephantulum) t. gracili ; lirulis circiter xx. haud acutis, 

 interstitiis hand profundis ; septo submamillato, submucronato ; 

 mucrone parvo, obtuso, subsiyiistrali ; marginel aterali convexo : 

 operculol . . . 



Long. -11, lat. -028. 



Hab. Panama, 2 sp. (C. B. Ad.). Mus. Amherst, Cuming. 



C. B. Ad. Pan. Shells, pp. 162, 311, no. 215. 



Known by the remarkable plug, which appears mamillate, but lias 

 a small apex projecting at the side. 



