mo i2 5] E. Guosu: The Anatomy of a Slug. 185 
Number of specimens. I | 20 Siting 4 Sth, Oo 
Length along the venter .. ot 7°8 7°6 vy) 6-9 6'9 6°4 
Length along the dorsum Bt vs 10'9 g'1 10 2 9 8°38 
Senne | aaa | | 
Width of the notum Ae ne Tet I‘O size) DO! 4 POs ae 
ee i pe 
Height of the notum ne sts 1'4 163 IZ 1g 2 KZ 
Width of the foot be a 7 ‘6 65 65 6 J 
Distance of the male genital aperture 
from the anterior end of the foot .. a 2h et 3 | ag 3 
= a z= > | 
Distance of the female genital aperture | 
from the anterior end of the foot .. Tea leeetgeh) 15215 173 ie3h eres 
= Seas Ee — wea * 
Length of the ommatophore 18 3 ah eae oe Bir aa, se 
Length of the lower tentacle PA ee US. |\ Re aa Mantle Beng 15 
Length of the cephalic flap Mada aelty Roe ae ker nea 3 
ae Oe : jeer sri | = 
Width of the flap Yunis PE ee oan sine 3 
ANATOMY. 
i =DODY, WALL. (pl, xxv, fie. 3). 
Minute structure—The body wall consists of the following 
layers !— 
(1) The epidermis consists of a single layer of epithelium. 
The cells of the epithelium are columnar in shape and 
are placed side by side except at their extreme 
narrow ends of attachment, where they are a little 
separated from each other. The free borders of the 
cells are refractile and striated, but it is doubt- 
ful whether they are ciliated. The protoplasm is 
granular and is marked with faint longitudinal 
striations. The nuclei are large and oval, and 
are placed in the middle of the cells. The attached 
narrow ends of the cells probably contain brown 
pigment granules in some places. Between these 
epithelial cells are scattered fine ducts of unicellular 
