Sporozoa 301 



flexible. Sporocysts are lacking in a few cases; in others, the oocyst con- 

 tains one, two, four, or many sporocysts. The number of sporozoites within 

 each sporocyst also varies from one to many. 



The following genera have been assigned to the family: Barrouxia Schneider (Fig. 

 6. 18, N, O), smooth oocyst containing many sporocysts, each with one sporozoite; 

 Caryospora Leger (51), oocyst containing one sporocyst with eight sporozoites; Cyclo- 

 spora Schneider (Fig. 6. 18, T), oocyst with two dizoic sporocysts; Dorisiella Ray (110; 

 Fig. 6. 18, Q-S), zygotes (apparently with a very delicate oocyst membrane) producing 

 two sporocysts, each with eight sporozoites; Ecfiinospora Leger (Fig. 6. 18, M), spiny 

 oocyst containing 4-8 bivalve sporocysts, each with one sporozoite; Eiineria Schneider 

 (6; Fig. 6. 18, A-K), oocysts containing four dizoic sporocysts, many species known from 

 mammals, birds, reptiles. Amphibia and fishes, and a few from Arthropoda; Isospora 

 Schneider (6; Fig. 6. 18, L), oocyst with two tetrazoic sporocysts; Jarrina Leger and 

 Hesse (Fig. 6. 18, P), oocyst with an elevated collar surrounding the micropyle, four 

 dizoic sporocysts; Pfeiffcriuella ^V'asieIewski (Fig. 6. 14, H), oocyst with eight sporozoites 

 but no sporocysts; Wenyonella Hoare (51), oocyst with four tetrazoic sporocysts. 



Fainily 5. Lankesterellidae . Sporozoites, developed within the asporo- 

 cystic oocyst, are liberated in the vertebrate host and enter erythrocytes. 

 Invaded corpuscles are ingested and transferred mechanically by an in- 

 vertebrate vector (mite, leech). The merogonic cycle is then resumed in 

 the new vertebrate host. In Shellackia Reichenow (Fig. 6. 19, A-F), de- 

 velopment occurs in the intestinal epithelium of lizards. Sporozoites 

 which have entered red corpuscles are transferred mechanically by a mite. 

 In Lankesterella Labbe (100, 100a; Fig. 6. 19, M), development occurs in 

 the endothelial cells of capillaries in frogs. Sporozoites, after entering 

 erythrocytes, are transferred by a leech. 



Family 6. Selenococcidiidae. The details of sporogony are unknown. 

 The reported phases of the life-cycle are unusual in that growth stages of 

 both schizonts and gametocytes are extracellular but enter tissue cells 

 to complete their development. The only genus, Selenococcidinyn Leger 

 and Duboscq (79a; Fig. 6. 19, G-L), contains a species reported from the 

 intestine of lobsters. 



Subclass 3. Haemosporidia 



These are the typical blood parasites whose gametocytes, and also 

 the merogonic cycle in some cases, occur in red blood cells. Syngamy and 

 sporogony occur in an invertebrate host. The zygote becomes a migratory 

 ookinete. Although an oocyst may be developed later, the membrane is 

 never a thick, resistant covering. Sporozoites are never enclosed in a 

 sporocyst membrane and inoculative transfer is the rule. In the Plasmo- 

 diida, the stages which invade red blood cells deposit pigment in their 

 cytoplasm, but this apparently is not true for the Babesiida. Malarial 

 parasites are known to split hemoglobin into globin and hematin, digest 

 the protein, and retain the hematin in characteristic pigment granules 

 (90). 



