GREGARINIDA 299 



suborder Schizogregarinaria. When the parasites are passed in 

 the feces of the host crab, the gymnospores enter the gill of a 

 mollusc and there undergo copulation (Hatt). The zygotes 

 develop into naked or encapsulated elongate vermiform bodies 

 which, when taken into a host crustacean, develop into tropho- 

 zoites. Several species. 



Porospora portunidaruni Frenzel (Fig. 125, p). The tropho- 

 zoite is very large. In the crab, Portunus, and the mollusc, 

 Cardium. 



Genus Dendrorhynchus Klein. Body elongated. Epimerite 

 a disc, surrounded by numerous ramified papillae. Cyst ellip- 

 tical; spores spindle-shaped (?). 



Dendrorhynchus system Keilin. Fully grown trophozoite 250 

 microns by 20 microns. The spore measures 19 microns by 7 

 microns. In the midgut of larvae of a dolichopodid fly, Systenus 

 sp., found in the decomposed sap of the elm tree. 



Suborder 2 Schizogregarinaria Leger 



The Schizogregarines are intestinal parasites of arthropods, 

 annelids, and tunicates. When the spore gains entrance to the 

 digestive tract of a specific host through the mouth, it ger- 

 minates and the sporozoites are set free (Fig. 126). These sporo- 

 zoites develop into trophozoites either in the gut-lumen or 

 within the host cells, and undergo schizogony (c), which may be 

 binary or multiple fission or budding. The fully grown tropho- 

 zoites become paired as in Eugregarinina and encyst, in which 

 condition they undergo sexual reproduction followed by sporo- 

 gony. Each individual which is now a gametocyte, produces 

 gametes id-e). Fusion of two gametes follows (/). The zygote 

 develops into a spore containing one to eight sporozoites (g, a). 

 Several genera. 



Genus Schizocytsis Leger. Mature trophozoite multinucle- 

 ate; ovoid or cylindrical with differentiated anterior end. Schiz- 

 ogony by multiple division. The trophozoites become associ- 

 ated, encyst, and produce a large (up to 30) number of spores, 

 each of which contains eight sporozoites. In Diptera, Annelida, 

 and Sipunculoida. 



Schizocystis gregarinoides Leger (Fig. 126). In the gut of 

 Ceratopogon larvae. 



