180 WHEELER. Vox. LX. 
were not seen in the marginal nerve of Syxcelidium. In 
regard to the brain, I must dissent from Woodworth, who 
regards the ‘Substanzinseln” as consisting of connective 
tissue, and the mass of closely-packed cells with large nuclei 
surrounding the fibrous portion of the brain as mesenchyma- 
tous. In Syucelidium it is possible to entertain some doubt 
in regard to the exact nature of these cells, because of their 
small size; but in B. candida, both the “ Substanzinseln’’ and 
the enveloping cells are undoubtedly ganglionic. It is even 
possible in this form to trace the single process of each 
ganglion cell into the felted mass of brain-fibres. 
In &. propinqua, the brain with its ganglionic covering is 
separated from the surrounding tissues by a layer of peculiar 
fibrous tissue. In specimens mounted zz foto, this layer 
appears as a pale halo surrounding the brain, and considerably 
increasing its apparent size. 
The eyes of Bdelloura and Syncelidium, always two in 
number, consist of oval refractive bodies set in pigment-cups, 
the latter being confined to the inner and lower surfaces of the 
bodies. The eyes lie, one on either ‘“Substanzinsel,”’ and 
appear to be innervated by very short fibres from this region 
of the brain. 
7. Male Reproductive Organs. 
The testicular follicles (Fig. 4 ¢s) are a series of oval, or, 
very rarely, lobed bodies which lie on either side of the body 
between the successive gut diverticula. They extend from the 
second or fourth diverticulum of the anterior ramus to the 
second or third diverticulum of the unpaired stem. They vary 
considerably in number ; in twenty specimens in which they 
were counted, there were 8—20 on either side of the body, the 
average number being 14. In the same individual the number 
on both sides is rarely equal ; one side usually exceeds the 
other by from one to four follicles. 
In B. candida the testicular sacs are much more numerous 
(60-100 on either side), and each sac is relatively very much 
smaller. Moreover, they lie outside the tips of the gut diver- 
ticula rather than between them. In ZB. propingua the testicular 
