298 E. A. MINCHIN. 



granules. The nucleus has a distinct membrane, and contains 

 a granular (?) fluid in which floats a single nucleolus of pecu- 

 liar vacuolated structure. The cysts are formed free in the 

 body-cavity. The protoplasm segments to form sporoblasts, 

 which develop each into egg-shaped spores, with a funnel-like 

 expansion at the narrow end, and a caudal process formed 

 from the outer layer of the cuticle at the broad end. The 

 spore contains eight nucleated falciform bodies embedded in a 

 granular '' nucleus de reliquat/' and each provided with a 

 flame-shaped tail. 



Habitat. — Intestine, blood-vessels, and coelom of Holo- 

 thuria tubulosa at Naples and Nizza. 



We shall now proceed to discuss the systematic position of 

 these Gregarines. But first it is necessary to consider one 

 question : are these binucleated adult forms to be looked upon 

 as one individual or two ? The only author, as far as I know, 

 who has touched upon this point is Mingazzini (5), who con- 

 siders each specimen to represent a pair of conjugated adults ; 

 without, however, excluding the possibility of their double 

 nature being due to fusion of a single individual. He further 

 describes the animals as divided by a septum, on each side of 

 which is one of the nuclei. I have not been able to see a 

 trace of this septum, and much doubt its existence ; neverthe- 

 less I am inclined to consider Mingazzini's view as the 

 correct one for the following reasons: (1) there are no cases 

 known in which it is the normal condition for a Gregarine to 

 have more than one nucleus ; see on this point Butschli (6, 

 p. 523) ; (2) though it cannot yet be said by any means to be 

 the rule, yet, whenever the life history of a Gregarine has 

 been carefully observed, it is found in the majority of cases 

 that two individuals fuse to form a cyst, whereas here a cyst 

 is formed from a single binucleated adult; and (3) I would 

 call attention to the peculiar Gregarines figured by Sars (3, 

 pi. xvi, figs. 2, 3, 5, G, and 7, a, and fig. 8), observed by him in 

 the intestine and blood-vessels of Chiridota Isevis, Fabr. sp. 

 (= Ch. pellucid a, Vahl sp.). Here one sees little Grega- 

 rines attached to the tissues, always in pairs, but quite distinct 



