CoTTREr.i.. — Audloinj of Siplidiiaiia nbli(|uata. 



587 



a.rranii;od in trjitisvcrse rows, the average iiuml)cr of teeth in each row being 

 a.l)Out 120. Each row contains three ki}ids of teeth, and these are found 

 in definite positions on the raduh^ : — 



1. A median tooth. This tooth is about half the size of those immediately 

 to the right or left ; it is conical and symmetrical (fig. 2 ; mt). 



Fig. 2. — Radula (x 370), showing Median and Admedian Teeth. 

 at, x^dmedian tooth; mt, median tooth. 



2. To the right and left are a large number of admedian teeth, each of 

 which is roughly conical, and on its outer side has a notch which gives rise 

 to a second cusp about the middle of the outer side of the tooth (fig. 2 ; at). 



3. The lateral teeth resemble the admedian, but each has three cusps ; 

 the median one is large, and, instead of being pointed, is broad and rounded : 



the lateral cusps, one on each 

 side, are small, pointed, and 

 occupy a corresponding posi- 

 tion to those of the admedian 

 teeth (fig. 3). Each radular 

 tooth has a basal portion 

 which is imbedded in the 

 chitinous membrane support- 

 ing the teeth. 



There is no sharp line of 

 demarcation between ad- 

 median and lateral teeth, 

 but one series graduates into 

 Fig. 3. ' ^^^ other. 



Radtjlar Teeth ; x 370. 



Fi<c. 3. Side view of admedian tooth, showing base (h) 



and point (p). 

 Fig. 4. Lateral tooth, sliowing the three cusj^s {a, h, c). 



The salivary glands are 

 lobulate structures composed 

 of large gland-cells with large 

 round nuclei, which stain very 

 deeply in borax carmine. 

 Each gland tapers posteriorly, and the two are connected by a string of little 

 lobes passing from the posterior end of one to the posterior end of the other. 



