202 HUGH WATSON. 



certainty from an examination of their external characters 

 only. It will be noticed that this race of A. gibbon si seems 

 to have a more westerly distribution than the preceding- 

 forms. 



Apera parva n. sp. 



External Characters (PL VIII, figs. 22, 23). — Animal 

 very slender, tapering to an acute angle at the hind end. 

 Back rounded, without keels. Outer lip of respiratory open- 

 ing almost concealing the inner lip. Skin coarsely reticu- 

 lated. Dorsal grooves about ^ mm. apart, separated by a 

 single row of rug«, but united for 3 mm. in front of the 

 respiratory opening. Lateral grooves near the dorsal grooves 

 and extending forwards to the head, the right one ending in 

 the genital opening. Radial grooves well-marked, but fewer 

 than usual, only three arising from the respiratory opening 

 on each side (in addition to the two median grooves). 

 Oblique sub-lateral grooves less numerous than in A. 

 gibbon si, being absent from the anterior third of the 

 animal. Both radial and sub-lateral terminate in the single 

 peripodial groove. 



Mr. Farquhar informs me that the living animal is fawn- 

 coloured ; dark dorsally, but much lighter below. In alcohol 

 the specimen has become yellowish brown, as shown in the 

 figures. 



The following are the dimensions of the slug in alcohol ; 

 but when alive and moving Mr. Farquhar tells me that it 

 attained a length of about 35 mm. 



Length . . 25 mm. Greatest height . 3 mm. 



Breadth in middle 3 „ Distance from resp. 



Bi-eadth at resp. opening to hind 



opening . . 2*4 „ end . . . 5*5 „ 



Breadth of foot-sole I'd ,, 



Internal Characters. — Skin very thick. Shell (PI. XIII, 

 fig. 44, 45) 1*6 X "9 mm., thick, depressed, with a flattened 



