206 HUGH WATSON. 



Length . . . 32'5 mm. . 38'5 mm. 



Breadth in middle . 6'5 „ . 7'5 ., 



Breadth at respiratory 



opening- ... 4 „ . 4"75 ., 



Breadth of foot-sole . 3-75 „ . 4-25 „ 



Greatest height . 6 „ . 6*5 „ 



Distance from respira- 

 tory opening to 



hind end . . 6 „ . 6*25 „ 



Internal Characters. — Skin not quite so thick as in most 

 of the species (PI. XI, figs. 34, 35 ; PI. XII, figs. 36-39 ; 

 PL XIII, fig. 40). Shell (PI. XIII, fig. 46) 3 x 1-8 mm., 

 thin and translucent, convex ; apex rounded, quite at the 

 posterior end ; sinus rather shallow. 



Pedal gland (PI. XIII, figs. 54, 59-62; PI. XIV, fig. 66).— 

 It has the glandular tissue entirely concentrated in the 

 anterior half, which is vei'y broad in consequence ; fold of 

 terminal vesicle not divided into nai^row lamellae. 



Nervous System (PI. XIV, figs. 68, 69; PI. XV, figs. 

 71, 73, 75; PI. XVI, figs. 80-86).— Cerebral ganglia with 

 prominent accessory lobes; buccal ganglia normally situated 

 posteriorly, joined to cerebral ganglia by comparatively short 

 connectives ; nerves to pedal ganglia large. 



Digestive System (PL XVI, figs. 88-90; PL XVII, 

 figs. 103-107; PL XVIII, figs. 115-122; PL XX, fig. 127; 

 text-fig. 4,B, p. 161; PL XXI, fig. 132; PL XXII, figs. 136, 137). 

 — Padula 4'8 mm. long ; central tooth absent; about thirteen 

 laterals with very short curved cusps, and the same number 

 of marginals with longer narrower cusps, on each side : 

 corresponding teeth not opposite to each other ; formula : 

 (25 -t- + 26) X 61. Odontophore rather large, with a 

 single buccal retractor. CEsophagus nai*row and as long as 

 the salivary ducts ; crop swollen anteriorly ; loops of wide 

 intestine nearly vertical, mainly on the left side of the 

 posterior division of the liver. Salivarj'' glands united above 

 anterior end of crop. Anterior division of liver above crop 

 and in front of intestine. 



