280 E. A. MINCHIN. 



even the stalked vesicles ciliated, but since they finally fall oflF 

 into the body-cavity he thinks that at a certain period they 

 would cease to be ciliated. 



The author further figures the mature psorosperm, and 

 identifies as a stage in the evolution of the Gregarine certain 

 amoebae forming the chief mass of the brown bodies. They 

 are homogeneous, without nucleus, and of fat-like contours. 

 For the most part they move slowly or are motionless. A 

 gradation of size could be found in these amoebae up to bodies 

 as large as the smallest or middling-sized Gregarines. 



In 1861, Sars (3, pi. xvi, figs. 2 — 7) figured Gregarine-like 

 bodies from the gut of Chiridota pellucida (= C. Isevis). 

 Since this date no further works dealing specially with these 

 organisms have, to my knowledge, appeared until the year 

 1891, when Cuenot (4) and Mingazzini (6) published re- 

 searches upon the Gregarines of Holothurians quite independ- 

 ently of one another. Ludwig (10) also gave an account of 

 the parasites of Holothurians, together with a complete litera- 

 ture of the subject. 



Cuenot (14) places the Gregarines of Holothurians in the 

 genus Syncystis, Aime Schneider, and describes three species, 

 Syncystis synaptse, E. R. L., sp., from the ca3lom of Sy- 

 napta inhserens, S. holothurise. Ant. Schneider, sp., from 

 Holothuria tubulosa, and S. Miilleri, Giard, sp., from 

 the coelom of Synapta digitata. Mingazzini (5), on the 

 other hand, places these Gregarines in the family Syncys- 

 tidse, but erects for them a special genus Cystobia, of 

 which he describes two species, Cystobia holothuriae, Ant. 

 Sch., sp., and C. Schneideri, n. sp., from Holothuria 

 Poli and impatiens. Further details in these authors' works 

 we shall refer to below under the special descriptions of these 

 Gregarines.^ 



' It should be mentioned that in 1852 Leydig described " dark plauarian- 

 like bodies, with egg-like structures embedded in them," and vesicles con- 

 taining pseudo-navicellse floating free in the body-cavity of Synapta digi- 

 tata (' Archiv f. Anat. u. Physiol./ 1852, in " Anatomische Notizen iibcr 

 Synapta digitata," pp. 517, 518, Taf. xiii, fig. 11). 



