58 H. M. WOODCOCK. 



in C. irregularis^ where tliey are firm and do not easily 

 become distorted in appearance. Neither have I noticed any 

 deeply-staining ping at the base of the funnel^ such as is 

 apparent in C. irregularis, although the spores oi 

 C. minchinii are similarly stained. Hence it seems to me 

 probable that in this species the delicate sporocyst itself is 

 dissolved. I have no doubt this difference in structure stands 

 in relation with the different method of infection, the dis- 

 solving power of the excretory acids, etc., in the respiratory 

 trees being, probably, much less than that of the gastric or 

 intestinal secretions of Holothuria. 



The contents of the spore, on the other hand, are readily 

 made out. There are, as usual, eight sporozoites, in this 

 case arranged in two distinct groups of four — one near either 

 end of the spore; in the centre lies the sporal residuum (s.r.), 

 separating the two groups. Two sporozoites are drawn 

 separately at h. Each is small and spindle-like, and possesses 

 a deeply-staining, square to rounded nucleus, situated near 

 the centre. 



[h] Systematic position. 



We are now in a position to compare the principal species 

 hitherto included under the generic heading of Cystobia. 

 (For C. holotliuriae see p. 3). It will be at once apparent 

 that C. irregularis and C. minchinii are more nearly 

 related to each other than is C. liolothuria3 to either. The 

 two former agree as regards the shape of the spore, which is 

 usually considered to be the principal classificatory character 

 in a Gregarine; moreover, their distribution, which is 

 apparently very limited, also narrowly coincides. In both 

 these respects C. holothurias differs markedly. The fact 

 that association is terminal in C. irregularis and lateral in 

 C. minchinii is not one that can be allowed to outweigh 

 the moi'e fundamental points of agreement just mentioned,^ 



' There is the same difference in the manner of association iu two closely 

 allied species of Gonospora, namely G. varia and G. sparsa. 



