26 



Observations on the Terrestrial 



seen still finer revolving ribs; incremental striae irregular and 

 extending over the ribs are also present. {Plate 2, Fig. 3.) 



Buccal plate, [Fig. 62,) curved, tapering later- 

 ally from the centre, striae radiating from centre 

 Fig. 62. of cutting edge, which is slightly projecting. 



Lingual membrane, 77-12-1-12. Lateral plate long, narrow, with a projection 

 at its outer posterior angles, tridentate, denticles minute, laterals nearly square, 

 outer posterior side thickened and produced, having one long denticle occupying 

 the centre of plate, with a smaller denticle occupying each side, at its base, 

 uncini denticulated, those nearest laterals having three or four rounded den- 

 ticles. (PI. 8, Fig. 63.) 



Strobila labypinthica. {Fig. 64.) 



Occurs throughout the state, in some places in abundance. 

 White specimens of this species have been observed. Animal 

 quite small compared to the size of the shell, 

 superior tentacles thick, bulbous, head broad, 

 eyes very large. The upper portion of the 

 whorls of the shell is deeply ribbed, {Plate 2, 

 Fig. 12, a,) while the lower portion or base of 

 the shell is very lightly ribbed and marked with 

 arborescent rugo3. {Plate 2, Fig. 12. b.) 

 The shell of this species has always been described as having 

 one revolving tooth within the aperture, and sometimes a second 

 one terminating farther within the aperture. I have always found 

 this second one constant, and also a third one but slightly raised 

 between these two. 



At the base of the shell and far within the aperture are two 

 more revolving ribs, running about a 

 third of one volution. These are plain- 

 ly visible through the substance of the 

 shell. A heavy columellar tooth or rib 

 extends from a slight distance within 

 the aperture, nearly one volution back. 

 This columellar tooth thickens the sub- 

 Fig. 65. stance of the shell in the umbilical 



region and causes a distinct fold without the shell. {Fig. 65.) 

 A most sintjular feature is revealed in the structure of the 



