SPECIAL MORPHOLOGY AND TAXONOMY OF SPOROZOA 435 



2. Genus Schizocystis, Leger (1909). AVith the characters of the family; 



parasites of marine annelids and sipunculids. 



3. Genus Eleutheroschizon, Brasil (1906). Agamogamy by internal bud- 



ding. Parasite of scoloplos. 



Family 3. Seleniidse, Brasil (1905). Highly motile worm-like forms 

 parasitic in marine annehds and in GephjTea. An epimerite-like attachmg 

 organ and myonemes running the entire length of the body are present. 

 The sporozoites develop as intracellular parasites into agamonts which 

 reproduce by multiple division. The gamonts unite in pseudoconjugation 

 and form isogametes as in Eugregarinida ; the sporoblasts are spherical, 

 provided with spmes and give rise to four sporozoites. 



4. Genus Selenidium, Giard. With the characters of the family. 



5. Genus Selenococcidium, Leger and Duboscq (1910). Similar to Selen- 



idium in form and agamous reproduction but very much like the 

 Coccidia in gamete formation and absence of pseudoconjugation. 

 Parasite of the lobster; sporoblast formation unknown. 



Family 4. Merogregarinidae, Porter (1909). Parasites of the ascidian 

 Amouroecium (?); sporozoites and agamonts intracellular; sporoblasts with 

 eight sporozoites. 



6. Genus Merogregarina, Porter. With characters of the Family, 



Family 5. Porosporidse, Leger. These are large forms (up to 16 mm.) 

 found in the digestive tract of Crustacea. Full development is unknown; 

 in one species — Porospora legeri Beauchamp — two individuals become 

 encysted together and undergo what is reported to be agamogony, or the 

 formation of an inmiense number of so-called "gymnospores." In P. 

 gigantea the individuals undergo such a process of reproduction singly, the 

 "gjannospores" developing as gamonts in the mussel Mytilus edulis. It is 

 quite possible that such "gynmospores" are gametes in which case the 

 Porosporidse should be included with the Eugregarinida. Change of host 

 appears to be obligatory in Crustacea and lamellibranch mollusks. 



7. Genus Porospora, A. Sclui. (1875). Several species with characters as 



above. 



Family 6. Spirocystidae, Leger and Duboscq. Forms infesting prac- 

 tically all of the organs of Lumbriculus variegatus Mull. Agamogony and 

 gamogony occur in the same host, sporoblasts with one sporozoite, aga- 

 monts spirally wound or crescentic. 



8. Genus Spirocystis nidula, Leger and Duboscq; characters as above. 



Family 7. CauUeryellidse, Keilin. Intestinal parasite of the larva of 

 the dipteron Aphiochaia rujipes. The agamont gives rise to sixteen aga- 

 metes, gamonts come together in pseudoconjugation each formi:ig eight 

 gametes, sporoblasts elongate, oval, each with eight sporozoites. 



9. Genus Caulleryella, Keilin; characters as above. 



Sub-class II. COCCIDIOMORPHA, Doflein. 



While the Gregariiiida are practically limited to invertebrate 

 hosts and are typically lumen-dwelling parasites, the Coccidio- 

 morpha are widel^' distributed in all groups of animals and are 

 typically intracellular parasites in all stages of growth and repro- 



