384 SPOROZOA. 



cephalonts have not been met with, nor have we come across 

 any cysts or spores which may be definitely assigned to this 

 species. 



Habitat. — Intestine of Eunice siciliensis Grube : Andaman 

 Islands, Port Blair. 



Family SELENIDIID^ BrasH, 1907. 



The family includes a single genus. 



Genus SELENIDIUM Giard, 1884, emend. 

 Brasil, 1907, and Ray, 1930. 



Selenidium, Giard, 1884, p. 192. 



Polyrhabdina, Labbe, 1899, p. 48. 



Selenidium, Caullery & Mesnil, 1899, pp. 80-99 ; Minchin, 1903, 

 p. 204 ; Brasil, 1907, pp. 370-97 ; Brasil & Fanthani, 1907, 

 p. 518; Wenyon, 1926, pp. 1127, 1136-8; Reicheuow, 1929, 

 pp. 876-7 ; Ray, 1930, pp. 370-98 ; Reichenow, 1932, pp. 22-5 ; 

 1935, p. 366. 



Trophozoites elongate, vermiform, very narrow and cyhndri- 

 cal or wider and more or less flattened, with longitudinal 

 myonemes along the entire length of the body. The anterior 

 end of the body is provided with a small knob-like organ of 

 fixation, and usually contains characteristic chromatic 

 bodies. Schizogony, where known, takes place during the 

 intracellular condition of the parasite. Gametocyst, where 

 known, contains many oocysts, each containing either four 

 or eight sporozoites. 



Remarks. — Ray (1930) has re-studied several imperfectly 

 known species of this genus and described several new ones. 

 He has shown that intracellular schizogony does not normally 

 occur in the majority of species studied by him, and is, in fact, 

 known to occur in two species only. He lays stress on the 

 occurrence, in all the species examined and at all stages of 

 their development, of characteristic chromatic bodies at the 

 anterior end of the animal. These are usually thread-like, 

 sometimes club-shaped, but always of a definite type and length 

 in any particular species, and usually fairly constant in number. 

 Very little is known about sporogony in the species of this 

 genus. In two species gametocytes were seen by Caullery 

 and Mesnil in association in the gut, and according to them the 

 attachment was by their anterior ends. Ray found that in 

 the species examined by him the associates become attached 

 by their posterior ends. Spores had been previously seen in 

 one species only, and were known to contain four sporozoites. 

 Ray found gametocysts and spores in two species, and the 

 spore contained four sporozoites in one species and eight 



