298 Sporozoa 



Family 1. Aggregatidae. Several to many sporocysts, in some species 

 several hundred, are developed within the oocyst. In Aggregata, merogony 

 occurs in crabs and syngamy and sporogony in cephalopods; in Ovivora 

 both phases of the cycle are completed in one host. Life-cycles are incom- 

 pletely known for various other members of the family. 



Fig. 6. 17. A-E. Cryptosporidium parviim, x3200 (after Tyzzer): tropho- 

 zoites (A); schizont (B); merogony (C); microgametogenesis (D); oocyst with 

 four sporozoites (E); all stages extracellular, on surface of intestinal epithelium 

 (mice). F-H. Aggergata eberthi (Labbe): sporoblast before secretion of sporo- 

 cyst membrane (F), x2000; lateral and polar views of sporocyst containing 

 three sporozoites (G, H), x2200 (after Dobell). I. Sporocyst of Myriospora 

 trophoniae, Avith sporozoites (after Lermantoff). J. Oocyst of Caryotropha 

 mesnili, with several sporocysts; x535 (after Siedlecki). K, L. Ovivora thalas- 

 semae (after Mackinnon and Ray): egg of Thalassema containing two parasites 

 (K), x240; sporocyst with 10 nuclei (L), xl440. 



The following genera have been included: Aggregata Frenzel (29; Figs. 6. 14, D; 17, 

 F-H), oocyst containing many sporocysts, each with 3-16 sporozoites in different species; 

 Angeiocystis Brasil, oocyst with four sporocysts, each containing about thirty sporozoites; 

 Merocyslis Dakin (21, 105), two sporozoites in each of many sporocysts; Myriospora 

 Lermantoff (82; Fig. 6. 17, I), oocyst with a few hundred sporocysts, each with 24-36 

 sporozoites; Ovivora Mackinnon and Ray (88; Figs. 6. 13, A, E-G; 14, B, C; 17, K, L), 

 many sporocysts, each with about twelve sporozoites; Pseudoklossia Leger and Duboscq 

 (81), oocyst with many dizoic sporocysts, sporogony in Pelecypoda, but merogonic cycle 

 unknown. 



