558 PROTOZOOLOGY 



merite unknown; cysts without duct; spores cylindro-biconical 

 (Labbe, 1899). 



L. agilis (Schneider) (Fig. 237, s). In gut of the larvae of Colym- 

 betes sp. 



Genus Phialoides Labbe. Epimerite a cushion set peripherally 

 with stout teeth, surrounded by a wider collar; with a long neck; 

 cysts spherical, without ducts; spores biconical. 



P. ornata (Leger) (Fig. 237, t-v). Sporadins 500/* long; cysts 

 300-400/x in diameter; spores 10.5/t by 6.7/*; in gut of larvae of 

 Hydrophilus piceus. 



Genus Geneiorhynchus Schneider. Epimerite a tuft of short 

 bristles at end of neck; spores cylindrical. 



G. aeschnae Crawley (Fig. 237, w). Sporadins 420// long; cysts 

 and spores unknown; in Aeschna constricta. 



Family 13 Porosporidae Labbe 



When naked or well-protected sporozoites enter the stomach 

 and midgut of a specific crustacean host, they develop into typi- 

 cal cephaline gregarines; 1, 2, or more sporadins become associat- 

 ed and encyst. Repeated nuclear and cytoplasmic division re- 

 sults in formation of an enormous number of gymnospores in hind- 

 gut. Some observers consider this change as schizogony, and hence 

 include the family in the suborder Schizogregarinina. When the 

 gymnospores are voided in the faeces of crustaceans and come in 

 contact with molluscan host, they enter, or are taken in by phago- 

 cytosis of, the epithelial cells of the gills, mantle or digestive system. 

 These gymnospores are found especially in abundance in the 

 lacunae of the gills. Presently they become paired and fuse (Hatt) ; 

 the zygotes develop into naked or encapsulated sporozoites within 

 the phagocytes of the molluscan host, which when taken in by a 

 crustacean host, develop into cephaline gregarines. 



Genus Porospora Schneider. Sporozoites formed in molluscan 

 phagocytes without any protective envelope (Hatt, 1931). 



P. gigantea (van Beneden) (Fig. 238, a-f). Sporadins in Ho- 

 marus gammarus, up to 10 mm. long; cysts 3-4 mm. in diameter; 

 gymnospores spherical, 8/i in diameter (Hatt), containing some 

 1500 merozoites; in molluscan hosts, Mytilus minimus and Tro- 

 chocochka mutabilis, they develop into naked sporozoites (17/* long) 

 which are usually grouped within phagocytes. 



Genus Nematopsis Schneider. Development similar to that of 

 Porospora (Hatt); but each sporozoite in a double envelope. 



N. legeri (de Beauchamp) {Porospora galloprovincialis L6ger and 



