1896. SPOROZOA. 113 



It is chiefly based on Aimee Schneider's system. The form and 

 number of the spores is about as natural a basis of classification of 

 the Sporozoa as was the Linnean staminal system of phanerogamous 

 plants. It is neither more nor less than absurd to place Monocystis 

 with the Actinocephalidae. The classification which I proposed in 

 the " Encyclopaedia Britannica " (Zoological Articles — Protozoa) at 

 any rate takes account of important structural features in the full- 

 grown active form of the organism. I do not think that at present 

 any further division of the Gregarinae than that into the order 

 Haplocyta, with the single genus Monocystis, and the order Septata, 

 with the two genera Gregavina and Hoplorhynchus, is useful, and it 

 seems to me that further generic distinctions should be sought in 

 characters of a less trivial nature than the form of the spores. 



I observe that none of the recent writers have re-studied my 

 Monocystis aphwditce, a monocystic form with a long proboscis of 

 peculiar character resembling the epimerite of some Septata. This 

 species is not uncommon in the alimentary canal of the larger sea- 

 mouse [Aphrodite aculeata), and is worth re-examination. Probably it 

 should be the type of a new genus. 



In regard to the Coccidiidea (which ought not to be called, as 

 they are by Wasielewski, by the generic title Coccidia), the spore- 

 containing cysts are so much more dominant in the life-history than 

 the unencysted " Euglenoid," that there is sufficient excuse for classi- 

 fying them in reference to their sporulation. But here, too, I note the 

 omission of an interesting form described and figured by me in the 

 article " Protozoa " above cited, viz., Klossia chitonis — which is 

 extremely abundant in species of chiton on the English coast. It 

 would come under Schneider's genus Barroussia. 



It is also important to correct an omission by Dr. von 

 Wasielewski of a sporozoon discovered in my laboratory at Oxford, 

 and described and figured by Miss Pollard in Quayt. Jouvn. Microsc. 

 Sci., vol. xxxiv., January, 1893. This interesting form is parasitic in 

 the epithelial cells lining the intestine of Amphioxus lanceolatns. It is 

 sickle-shaped, resembling a Drepanidiiim, and causes a distortion and 

 atrophy of the nucleus of the cell in which it is parasitic. Its spore- 

 formation has not been observed, and no generic or specific name was 

 assigned to it by Miss Pollard. 



The separation of the order Haemosporidia from the order 

 Acystosporidia appears to me to be unnatural. The Acystosporidia 

 are only a step further advanced in degenerative cell-parasitism than 

 the Haemosporidia, and should not on that account be made into a 

 distinct order. It may, however, be noted that Grassi thinks the 

 Acystosporidia are not Sporozoa at all, but to be placed near Amoeba 

 and the Mycetozoa. 



The Drepanidium ranarum, described and figured by me in 1871, 

 and so designated by me in 1882 {Quart. Journ. Microsc. Sci., vol. xxii., 

 p. 53), has become the prototype of a number of blood-parasites. 



