246 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



nized among the Geophila of presence or absence of a jaw, or of aculeate or 

 quadrate teeth. By the modern arrangement these two genera are most widely 

 separated. 



The surface of the animal is dirty white, with about seventeen vertical rows, 

 on each side, of dark blue or slate blotches, interrupted by the longitudinal 

 reticulations running parallel to the foot, but again commencing and extending 

 to the edge of the foot. These blotches diverge in all directions from under 

 the shell and mantle, running almost perpendicularly on the side of the animal, 

 but very obliquely in front and behind. The tail is quite keeled with oblique 

 blotches. These blotches also run obliquely from a median line on the fore- 

 part of the extended animal. Tentacles, eye-peduncles, and front of head slate- 

 color. Lips developed and kept constantly in motion as tentacles. The reticu- 

 lations of the surface are large and few. 



In specimens preserved in alcohol there appears a locomotive disk. There 

 is no caudal pore. The respiratory and anal orifices are far behind the centre 

 of the mantle edge on the right of the animal. The genital orifice appears 

 somewhat behind the right eye-peduncle. The mantle is scarcely reflected upon 

 the shell, even in front. When the animal is fully extended, Dr. Cooper says 

 the mantle equals one fourth of its length. The mantle exudes mucus freely. 

 It seems fixed to the shell, not changing its position with the movement of the 

 animal. 



One of the shells collected by Mr. Hemphill is twice as large as that whose 

 measurements are given by Mr. Bland and myself. 



The jaw is thick, slightly arcuate, ends blunt; anterior surface with six well- 

 developed ribs denticulating either margin, situated on the central third of the 

 jaw, and as many subobsolete ribs on each outer third ; no median projection 

 (Fig. 142). 



Lingual membrane (PI. V. Fig. K) long and narrow. Teeth 31 1 31, with 

 about 15 laterals, but the change into marginals is very gradual, the latter 

 being a simple modification of the former. My figures give a central with the 

 first, sixteenth, and thirty-first teeth. 



The nervous ganglia and the digestive system present no peculiar features. 

 The genitalia are figured on PI. XI. Fig. B. The penis^sac is long, narrow, 

 tapering to its apex, where it receives the vas deferens ; the retractor muscle is 

 inserted below the entrance of the latter. The genital bladder is oval, on a 

 long, narrow duct. There is a small, sac-like, accessory organ, probably a dart 

 sac (</, s). 



HEMPHILLIA. 1 



Animal limaciform, small, blunt in front, tapering behind. Mantle sub- 

 central, large, oval, greatly produced in front, free around its margin and 



1 Animal limaciforme, parvum, antice obtnsnm, postice attenuatum. Pallium sub- 

 centrale, magnum, ovatiun, antice valde productum, margiuibus liberis. Discus gressorius 



