95 



283 



bombée et déprimée vers la tète. L'organe rotatoire est muni de toiifTcs de longs cils sensilifs 

 raides et ressemble à celui de la l'emelle. On aperçoit, comme chez la l'emclle, une sorte de 

 capsule transparente sur laquelle repose l'œil. Le testicule occupe une grande partie de la 

 ca%dté du corps, le pénis est long, mince, terminé par la couronne de cils et entouré d'ime 

 forte gaine chitineuse qui s'étend parallèment au pied et va de la lorica au deuxième anneau 

 du pied; la queue est rayée transversalement. Je n'ai pu voir ni organes digestifs, ni organes 

 excréteurs. Ce mâle est vif et saute à la façon de la femelle. Les muscles du pied sont au 

 nombre de deux paires. Time: July." 



Ploesomatidæ. 



The family contains one single genus Plocsoina with four species: P. hudsoni 

 Imh., P. triacantlmm Berg, P. lenticulare Herrick and P. truncatiim Lev. The males 

 are unknown. With regard to P. hudsoni Wierzejski and Zacharias (1893, p. 236) 

 only write that: 



Zacharias has observed the male. "Es zeichnet sich durch einen zelienlosen Fuss aus, 

 der wahrscheinlich als Copulationsorgan fungiert. An seiner Ur.sprungsstelle befand sich eine 

 mit Samen gefüllte Blase." 



Ploesoma Hudsoni Imh. 



Tab. XIV, flg. 5—6. 



Description. Body with parallel sides; somewhat flattened, a little broader 

 behind, covered with a conspicuous lorica ; dorsally provided with a series of thicker, 

 parallel longitudinal lines, two of which forming ellipses open anteriorly; ventrally 

 with a system of transversal ridges in a number of four round a little plate, behind 

 which most probablj' lies the opening for the penis. No foot observed; in swim- 

 ming it is always retracted, and I never succeeded in seeing it come out by means 

 of pressure upon the cover. In its anterior part the lorica dorsally bears medially 

 a rather stout tag and laterally some smaller indentations. Wheel-organ a ciliary 

 wreath with rather conspicuous auricles, surrounding a disc, which, when fully 

 expanded, presents some peculiarities; in the middle a cushion-shaped elevation, 

 covered with short cilia and laterally two protuberances, carrying a tuft of long 

 cilia; ventrally on the disc two long, thick fleshy club-shaped antennæ. The whole 

 body quite untransparent, greyish, filled with a peculiar granular mass, in which 

 are imbedded large quantities of oil-globules; of those, one especially is always 

 present; this globule, which is Ij'ing dorsally in the posterior part, and medially, is 

 very large; the peculiar foam-structure of the lorica in the female has not been 

 observed in that of the male. 



Owing to the intransparency of the body, only very little of the internal struc- 

 ture is seen. No brain is observed; only a dorsal antenna; laterally in two skin 

 folds are seen two strong, single sensitive hairs, long and stiff. Seen ventrally the 

 relatively small testis with the two sorts of spermatozoa has been pointed out, but 

 I have not succeeded in finding the ductus seminalis and a penis; also the whole 

 excretory organ has been undiscoverable. Above the testis is a large globular mass, 

 containing a number of sharp edged opaque grains. No muscle system was observed. 

 Size of male 80 fi, of female 400—500 /t. Time 23/VIII 21. 



