438 



TEMP.-MAJOR H. M. EVANS ON 



A nipple will extend for •3--4 mm., and there is then a. gap of 

 about '2 mm. until the next nipple appears on the lateial canal. 

 In this way the dentate margin is moistened with secretion, and 

 as the teeth lacerate the tissue of the victim the poison becomes 

 inoculated in the wound. Towards the tip of the spine there is 

 little glandular tissue : the central canal divides into two or more 

 channels, and the seci'etion is discharged by means of a canal, of 

 which thei'e are two on either side, a lateral canal near the base 

 of the teeth, and a canal resting on the margin of the median 

 I'idge where it looks towai'ds the lateral groove. 



Text-figure 7. 



Trj/gon pastinaca. 



Diagram of portion of spine to show scheme of canals and relations of 

 nipples and filaments. 



c.c. Central canal, c.r. canal of ridge, f.ff. follicles of gland. I.e. lateral canal. 

 in.r. median ridge. n.J.c. nipples of lateral canal, s.f. secreting filaments. 

 t. tooth pointing forwards. 



It is here that these lateral canals give ofi' the hollow filamentous 

 tubes, which pr(^)ject towards each other and are of such length 

 that the two make a bridge across the lateral groove. They 



