THE NATURAL HISTORY SURVEY, 329 
Animal; Color yellowish-white on foot and body; head 
and rostrum black with several yellow or golden-yellow spots, 
the tip of the rostrum yellowish-white. Rostrum rather large, 
rounded. Tentacles long and filiform, the black eyes placed 
on swellings at their lower outer base. The body appears 
speckled with black and yellowish-white through the shell. 
Foot wide, rather short, slightly auriculated before, whitish on 
Fie. 116. 
Operculum of ByTHINIA TENTACULATA Linné. (Original.) Enlarged. 
edge with a yellowish part near the center and toward the an- 
terior end. Cervical lobes (lappets) round, wide, short, rather 
fully extended. Verge rather large, placed as usual in the 
family. Operculum placed toward the posterior part of the 
foot, calcareous within, concentric; the rings of growth stand 
up in the form of ridges or scales, and their arrangement is 
quite regular (Fig. 116). The foot measures 6.50 mill. in length 
and 4.00 mill. in width. 
Radula formula: pstpeytttetetttistis (3-1-3); 
central tooth wider than high, ends produced and rounded, 
lower edge concave and with a rounded process extending 
from its center; lateral lobes armed with six to seven denticles 
7 
Fie, 117. 
Radula of BYTHINIA TENTACULATA Linné. (Original.) C. central 
tooth; 1, intermediate tooth; 2, 3, lateral teeth. 
which are rather long and roundly pointed, the denticulate 
portion extending from just beneath the reflection to the end 
of the lobes; reflection wide and low, seven-cuspid, the center 
cusp large and roundly pointed and the lateral cusps sharply 
triangular; intermediate tooth squarish, the lower outer corner 
produced; reflection wide and low, seven-cuspid, the third cusp 
