82 W. f!. lilDEWOOD AND R. H. FANTHAM. 



cens is found in relation Avitli the nervous, deeper layer of 

 the ectoderm. It does not always occur actually within that 

 layer, since it may bulge outwards into the more superficial 

 cells of the ectoderm, or may project inwards into the under- 

 lying- tissues, but the new organisms seem always to be 

 situated in the nerve tissue before they begin to enlarge and 

 sporulate. On account of this peculiarity we apply to the 

 organism the generic name Neurosporidium. Cephalo- 

 discus being the host in which the parasite has been 

 encountered, we base the specific name upon that. The 

 organism is thus denominated Neurosporidium cephalo- 

 disei. 



No unicellular parasites of Cephalodiscus have up to 

 the present been described. In Cephalodiscus gilchristi 

 there is a Copepod Crustacean occuri-ing parasiticiilly in the 

 stomach of a large proportion of the polypides ^ ; this parasite 

 is closely allied to the Copepods that occur in the g"ut of 

 Tunicates, and belong to the family Ascidicolidas of 

 Giesbrecht. 



Masterman^ has drawn attention to "cyst-like structures'^ 

 occurring near the anus of Cephalodiscus d o d e c a 1 o p h u s, 

 which he is disposed to regard as larva3 of Cephalodiscus. 

 but which from their position are more likely to be parasites. 

 They are of comparatively large size, and judging by the 

 large size of the cells as drawn in the figure, they are moro 

 probably the young of some metazoon parasite than cysts of 

 Sporozoa. 



M'Intosh ^ marks by the symbol 6p. a series of thi-ee spheri- 

 cal bodies occurring in the deeper part of the nervous layer 

 of the ectoderm, which might at first glance be taken for 

 Sporozoa. Their position is one commonly occupied by the 

 parasite which forms the subject of the present paper, and 

 their size and general shape carry the resemblance with 



' Ridewood, W. G., "Ceplialodiscus gilcliristi," 'Marine Invest. 

 South Africa,' iv, 1906, p. 181. 



5 ' Trans. Roy. Soc. Edinb.,' 1898, p. 513, last paragrapli ; also |.l. 5, fig. SG. 

 3 ' "Challenger" Reports,' part 62, vol. xx, 1887, pi. 6, fig. 3. 



