371 STUDIES ON GREGARINES—KAMM 37 



are cleared up by exhaustive researches. For these reasons I have raised 

 the genus Cephaloidophora to a new family, Cephaloidophoridae. 



Unlike other great groups of gregarines, the complete life-history of a 

 crustacean parasite must be known before it can be assigned to a particular 

 genus with a reasonable assurance of permanence; generally two out of 

 three or four characters will determine the location of a gregarine. Unless 

 the evolution of a sporozoite from the spore (Cephaloidophoridae) or from 

 the cyst direct (Aggregatidae) is known and the intracellular development 

 has been observed or proven to be absent, a crustacean parasite cannot 

 be accurately placed. Leger and Duboscq, the closest students of the 

 gregarines of the Crustacea, have removed many species hitherto classed as 

 gregarines to the family Aggregatidae, now placed in the order Coccidia, 

 because the sporozoites develop in the cyst without the intervention of 

 spores. The sporogonic cycle of the Aggregatidae is passed in another 

 host, a Cephalopod. Thus an alternation of hosts corresponds to an 

 alternation of generations, the crab being eaten by the Cephalopod. 



Another family of gregarines inhabiting Crustacea is the POROSPORI- 

 DAE, parasitic in Decapods only. These animals are very large, usually 

 but not always solitary in the adult and are capable of forming cysts from 

 a single individual. This raises the question that such cysts are schizo- 

 gonic cysts and that the sporogonic stage, which possibly has not been seen, 

 is passed in another host. 



Leger and Duboscq (1911 :lix) offer this hypothesis: 



.... si Cephaloidophora et Porospora ne tomberont pas en synonymie, Porospora 

 representant la schizogonie et Cephaloidophora la gamogonie d'un meme cycle. 



Tregouboff (1912) says, however: 



Je suis convaincu que les Cephaloidophora effectuent leur cycle dans un seul h6te et presentent 

 un seul ty\)t des germes. 



Minchin (1912:340) says: 



A character such as the power of multiplication by schizogony is clearly one of great adaptive 

 importance in the life-history of a parasitic organism, and therefore not likely to be of class- 

 ificatory value. The classification of the future will probably be one which divides all grega- 

 rines into Cephalina and Acephaljna, and distributes the Schizogregarines (into which 

 suborder the Porosporidae are now placed) amongst these two divisions. 



I think the last statement holds the clue to the classification of these 

 puzzling forms. Leger and Duboscq first placed two of their early forms 

 Cephaloidophora fossor and C. ocellata among the Aggregatidae, finding 

 only coelomic cysts. After more exhaustive researches they found a life- 

 history typically that of the genus Cephaloidophora, and removed the 

 species to this genus, considering that the coelomic cysts they had pre- 

 viously found belonged to different gregarines, of which nothing else was 

 known. I feel certain the latter really belonged in the same life-cycle 

 and that the power of producing coelomic cysts and their concommitant 



