SIXTEN BOCK, TWO NEW COTYL. GEN. OF POLYCLADS. 19 



The genus Diposthus with the singla species D. corallicola 

 is described by Woodworth (1898). The peculiarities of 

 its male sexual organs have necessitated Woodworth to 

 establish a new family, Diposthiidce, for the reception of this 

 genus. The penis and prostate gland are separated »into two 

 distinct organs, both of which are doubtless intromittent». 

 There are two large vesiculae seminales, the ducts of which 

 unite to form the ductus ejaculatorius. The female apparatus 

 possesses uterine vesicles which communicate with a common 

 duct, the ducts of opposite sides uniting to enter the female 

 atrium, which functions as a bursa copulatrix. Of the pha- 

 rynx it is only said that »it can be seen as a lighter ragged 

 median streak». To judge from the figure (1. c, Plate, fig. 

 6) it is situated in the centre of the body and must be of 

 the folded type; it probably has the pharyngeal chamber 

 provided with side pockets. There are also »two pointed 

 conical tentacles close to the anterior margin». 



The organisation of the male apparatus and the pharynx 

 separates Diposthus from the Psevdoceridce-Euryleptidce. The 

 female organisation agrees well with the Pericelidce, as does 

 very probably the pharynx (and perhaps the tentacles). As 

 both the male and female organisation, besides other features, 

 are unlike that of Chromoplana we have no reason to unite 

 these two genera in the same family. 



The genus Pericelis, constituting its own family (see 

 Laidlaw 1902 and Meixner 1907), still remains to be dis- 

 cussed. The single species has a very large, thin and exces- 

 sively folded body with two marginal tentacles. Besides the 

 cerebral eyes in two dusters, there are frontal eyes and a 

 complete series of marginal eyes around the whole body. 

 The pharynx is situated centrally and much crinkled (»krau- 

 senförmig> ). The intestine is richly branched with anasto- 

 moses between the branches. The male apparatus has a 

 backward directed fleshy unarmed penis without penis-folds. 

 Meixner says: »Eine besondere, deutlich abgesetzte Körner- 

 driisenblase fehlt Pericelis Beyerlana gänzlich, desgleichen 

 konnte ich extrakapsuläre, im Mesenchym ausserhalb der 

 Muskulatur gelegene Körnerdriisen nicht entdecken». The 

 ductus ejaculatorius can, according to Meixner, be divided into 

 a proximal »vesicula seminalis», a middle prostatic part with 

 granular gland cells in the epithelium, and a distal part, 



