20 



gations have not supported this opinion; and the 

 belief now is, that they are probably nourished by 

 imbibition through the skin. 



Beneath the head is the neck (PI. I. fig. 6, B), 

 varying in length (being sometimes developed, and 

 sometimes not), and does not possess articulations, 

 although by the microscope quite marked transverse 

 striations are visible. The articulations (PL II. fig. 

 3), which, according to Aitken, commence about 

 three inches from the head, likewise differ from those 

 of the Taeniae. At first being square, they become 

 broader than they are long, generally in the propor- 

 tion of 3 : 1 (Kiichenmeister) ; although, even here, 

 they become capable of variation. Each articulation 

 has two surfaces, a ventral (upon which are situated 

 the genitals) and a dorsal one ; and four margins, two 

 lateral, which are undulatory; and one anterior and 

 one posterior, by which it is joined to the segment 

 preceding and succeeding. As in the Taeniae, the 

 anterior articulations overlap the posterior ones, but 

 not in so marked a degree. 



The number of articulations which an adult Both- 

 riocephalus bears, has been reckoned by M. Eschricht 

 at 10,000 (Moquin-Tandon). In the centre they are 

 thicker than at the sides, up to 1 (Kiichenmeister), 

 and possess a dark-brown color, according as they con- 

 tain matured ova, becoming at the margins flatter and 

 whiter. 



The genital organs in this genus are situated, not, 

 as in the Taeniae, on the margins, but in the centre of 

 the articulations, and are recognizable as slight eleva- 



