ZOOLOGY 



Systematic Position of the Uxamplc. 



Monocystis agilis is a species of the genus Monocystis, belonging 



the family Monocystidcc, of the order Oregarinida. It is placed 



1 the Gregarinida on account of being free and motile in the tro- 

 hozoite state. The absence of partitions dividing the protoplasm 

 ito segments indicates its position among the Monocystidte. 

 lonocystis is distinguished by its elongated form, by the absence 

 f any special apparatus in the cyst for the liberation and dispersal 

 f the spores, and by its spindle-shaped spores with thickened 

 nds, each producing 4—8 falciform young. The differences 

 letween the species of Monocystis depend largely upon size. 



Order 1. — Gregarinida. 



All the more typical members of the class belong to this 

 ■roup. With the exception of Monocystis, already described, the 

 nly genus to which it will be necessary to draw attention is 

 rrcgarina (Figs. 62 and 63), the various species of which are 

 larasitic in the intestines of Crayfishes, Cockroaches, Centipedes, 



;. 62. — Greg^arina. A, two specimens of 0. hlattarum parUy embedded in enteric 

 C]7ithelial cells of Cockroach ; Bl, B^, two specimens of G. dujardini ; in B2 the epimerite {'p.) 

 is cast off ; C, cyst of G. hlatlariim, from which most of the spores have been discharged ; 

 D, four stages in tlie development of G. rilrjaulm. r//. cyst ; deu. deutomerite ; cp. epimerite ; 

 fl. gelatinous investment of cyst; nv. nucleus ; jn: protomerite ; ^wi?. 1, short pseudopod ; 

 jwL ,?, long pseudopod ; sp. mass of spores ; spd. sporoducts. (From Biltschli's Protozoa.) 



and other articulated animals. It differs from Monocystis in 

 having the medullary protoplasm of the adult divided into two 

 sections, an anterior, the protomerite {pr.), and a posterior, the 

 deutomerite (deio.), in which the nucleus is situated. Anteriorly 



