150 MOLLUSCA. 
sulcis et lirts alternantibus equalibus ad quatuor cinctis, coloribus 
cinereis et pallidé rufis partitis ; sutura impressa: apertura parva, 
semi-elliptica, antice emarginata ; columella viz arcuata ; labro acuto. 
Cerithium filosum, GouLp ; Proceed. Boston Soc. Nat. Hist., 11. 120. 
May 1849. Expedition Shells, 62. 
SHELL small, turritella-shaped, pale ash-coloured on the posterior, 
and pale brown on the anterior half of the whorls: these are about 
eight in number, flat, with a well-marked suture, each one of them 
sculptured with about four alternating ridges and grooves, of about 
equal width, the grooves regularly concave, the ridges sometimes 
subdivided by a very delicate groove; on the basal whorl are about 
ten grooves, growing gradually less conspicuous. Aperture small, 
less than one-fourth the length of the shell, semi-elliptical, with a mere 
basal emargination instead of a canal; lip thin and simple; columella 
slightly arcuated ; interior with ridges corresponding to the external 
grooves. 
Length five-eighths of an inch; breadth one-fifth of an inch. 
Inhabits Puget Sound, Oregon. 
Only a single specimen of this turritella-like Cerithium has been 
examined. It is of the same type as C. celatum, and is well-charac- 
terized by its simple revolving lines and grooves, and its coloration. 
Figures 175, 175, two views of the shell, enlarged; 175 8, details 
of sculpture; 175, natural size. 
CErRITHIUM PUSILLUM (Gould). 
Testa minuta, fulva, turrita, varicosa, longitudinahter undata, undis ad 
decem, prope basim evanescentibus: spira acuminata, anfractibus octo 
convexis, filis tenuibus granulosis quatuor cinctis, anfractu ultimo 
multicincto: apertura lata, ovata, obliqua; rostro brevissimo ; labro 
varicoso ; columella arcuata. 
Cerithium pusillum, Goutp; Proceed. Boston Soc. Nat. Hist., iii. 
120. May 1849. Expedition Shells, 62. 
