266 CERITHIOPSID.E. 



many species ; and doubtless more liave been placed or 

 retained in Cerithium, owing to a misapprehension of 

 the distinctive characters. 



1. Certthiopsis tubercula'ris"^, Montagu. 



Murex tubercularis, Mont, Test. Br. p. 270. C. tuberculare, F. & H. iii. 

 p. 365, pi. xci. f. 7, 8, and (animal) pi. 00. f. 1, 2. 



Body white, with three broad longitudinal stripes of dark 

 grey [the lateral ones composed of minute brown points 

 (Clark)], one along the neck, and another on each side : pallial 

 tube extremely short : head small and compressed : tentacles 

 rather short, slightly inflated at the base ['' banded or ringed 

 with lead-colour" (JF. & H.)]; tips blunt: eyes black, placed 

 rather close together [behind each are some sulphur-coloured 

 points (Clark)] : foot thick, squarish, and double-edged in 

 front, with small angular corners ; from each corner runs a 

 series of transverse flake-white plates (like those of the gill- 

 plume), which are imbedded in the tissue ; the foot is usually 

 protruded considerably beyond the head ; it becomes attenu- 

 ated behind, and ends in a blunt point; sole perforated in 

 the middle, whence a narrow but deep groove extends to the 

 tail : opercular lohe margined with yellow on each side. 



Shell cyhndro -pyramidal, with a narrow and somewhat 

 contracted base, which gives the C3^hndrical shape ; it is 

 solid, opaque, and glossy : sculpture, rows of small and close- 

 set tubercles (from 20 to 25 in the lowest row), caused by 

 the mutual decussation of sj^iral and longitudinal ribs ; of these 

 rows there are 3 on the body- whorl, above the periphery; 

 the tubercles on that whorl are oblong, and have their greater 

 axis in the line of the spire (by reason of the transverse ribs 

 being broader there) ; the other tubercles are granular or bead- 

 like, and proj)ortionally equal in size ; each of the preceding 

 8 whorls has also 3 rows ; the first 4 or 5 whorls are quite 

 smooth ; the base of the shell (which is slightly excavated) is 

 girded by 2 strong, rather broad and obhquely twisted spiral 

 ridges, one just below the periphery, and the other very short 

 and winding round the canal ; occasionally the upper of the 

 basal ridges is inchstinctly beaded, and in that case the lon- 

 gitudinal ribs may be traced below it : colour dark- chestnut 

 or chocolate : sjnre somewhat turreted ; the terminal portion 



* Covered with tubercles. 



