ZONITES. 99 



low the furrows. The breadth of the animal is very much greater than in most 

 of our species, the head broader, blunter, the eye-peduncles shorter, heavier, 

 and very much more widely set apart. A narrow Fig. 20. 



locomotive disk below. Along the side of the foot, 

 parallel to the base, are two furrows, rather darker 

 in color, running upwards towards the tail, and meet- 

 ing on its upper 'surf ace, above a mucus pore. The 

 extremity of the tail broad and flattened, spade-like, 

 usually curved at its point when the animal is in mo- 

 tion. The animal is more sluggish and less sensitive 

 to the touch than the other species. Its labial ten- Zonites capnodes. 



tacles are highly developed, being nearly as long as the lower feelers. Meas- 

 urements of an individual in motion : Extreme length of foot 59 mill. ; before 

 shell 16 mill.; behind shell 14 mill.; of shell on back 32 mill. ; of tentacles 

 10 mill. ; breadth of head 11 mill. 



I was at first inclined to consider it an unnaturally developed form of fuligi- 

 nosus, but have since been convinced of its being distinct by large suites of spe- 

 cimens of various stages of growth. The shell is larger, heavier, less globose ; 

 the umbilicus is narrower ; the aperture larger, and less rounded ; the spire 

 less elevated. The coarse, interrupted revolving lines are present in four out 

 of six specimens before me. The species is very variable, and in its globose 

 form difficult to distinguish from Z. friabilis. It is, however, always much 

 heavier. The globose form is figured (Fig. 20). 



Jaw as usual in the genus. 



Lingual membrane broad, with numerous rows of about 66 1 66 teeth. 

 Another membrane has 70 rows of 46 1 46. Centrals long, with a long, 

 slender, median cusp, reaching the base of attachment and bearing a long, 

 slender point projecting beyond it. Side cusps subobsolete, but represented by 

 the cutting points, which are greatly developed, triangular, stretching beyond 

 the sides of the base of attachment. Lateral teeth of same type as centrals, 

 but bicuspid ; there are about 9 perfect laterals. Marginals aculeate, as 

 usual in the genus (PI. II. Fig. K). 



I have not been able to observe the complete genital system of the species. 1 

 The penis has the same arrangement as in Z. Ueviyatus. The external orifice 

 is quite under the edge of the mantle. 



1 In the Land Mollusken of the Arcliip. der Philippinen (p. 78, PI. III. Fig. 27 ; 

 PI. V. Fig. 21), Semper describes and figures a genital system, jaw, and lingual den- 

 tition, which he refers to Z. lucubratus, SAY. The specimen examined by him was from 

 Tennessee. It is dillicult to decide from what species Semper drew his description. It 

 certainly was not the true lucubratus, which is a Mexican species. A comparison of my 

 descriptions and figures of Icevigatus, inornatus, fuliginosus, and friabilis shows that 

 neither of those species could have been before Semper. His description of the lingual 

 membrane would better apply to capnodes. I have not been able to examine the whole 

 of the genital system to see how nearly that also agrees with his figures. 



