4 n. M. WOODCOCK. 



of the blood-vcssols by a delicate stalk, and also^ when ripe, 

 floating free in the body-cavitj'. Spores ovoid, with the 

 epispore having the funnel at one end, and, in addition, nt 

 the other end a flat process like a lance-liead. Sporozoites 

 with rounded nucleus. Habitat : H. tubulosa, at Naples. 

 (Also in Chiridota pellucida, according to Sars.) 



(2) C. irregularis (Minchin). — Cysts always attached to 

 the wall of the blood-vessels. Spores ovoid ; epispore pi'o- 

 longed into a cup-like expansion, open to the exterior. The 

 sporozoites possess an elongated nucleus. Habitat : blood- 

 vessels of Holothuria f or s kali (H. nigra) . 



(3) C. schneideri, Ming. — Of smaller size, and much 

 less resistant to sea-water than the foregoing. [This is rather 

 a slight diagnosis on which to base a new sp.] Habitat : 

 H. polii and H. impatiens, Naples. 



It will be seen, therefore, that practically nothing has been 

 described for Cystobia with regard to such important ques- 

 tions as the processes of nuclear division preceding sporulation, 

 the formation of primary sporoblasts and their conjugation, 

 whether isogamous or anisogamous, etc. Nor was Minchin 

 able to make out at all satisfactorily the extent and intimacy 

 of association in C. irregularis, a point which is of great 

 interest and importance. A knowledge of these various stages 

 in the life-history was eminently to be desired, since during 

 the last few years much has been learnt respecting them in 

 the case of other Gregarines. It will be useful, first of all, to 

 outline briefly the results of recent research in this direction. 



Siedlecki (36) was the first to correctly work out the life- 

 cycle, which he did for Lankesteria ascidia3,a member 

 of the sub-order Ase ptata or Haplocy ta, parasitic in the 

 gut of Ciona intestinalis. Association occurs between two 

 equal-sized adults. The syzygy rotates and gradually becomes 

 spherical, and an outer and inner cyst-membrane are suc- 

 cessively laid down. After elimination of much of the nuclear 

 material, the remainder gives rise by successive divisions, 

 the earlier of which exhibit well-marked mitosis, to a number 

 of daughter- or micro-nuclei. Meanwhile the bodies of the 



