390 PROCEEDINGS OF THE ACADEMY OF [May, 



probably this thickening represents the germinal epithelium and there- 

 fore the testis {Test.) proper. A curled thick-walled tube, the cirrhus, 

 follows the sperm sac; its lumen, the vas deferens (V.D.), is very 

 narrow. A thin-walled short tvibe connects the posterior end of this 

 cirrhus with the dorsal genital aperture; and wdthin this tube beat 

 long cilia which are attached to the posterior end of the cirrhus. The 

 cirrhus may be protruded some distance out of the genital aperture, 

 and probably serves as an intromittent copulatorj^ organ. On the 

 ventral side of the cirrhus, in close attachment to its wall, is a large 

 dense body (Gl.) with an axial pyriform clear space; I interpret this 

 to be a gland, and the clear space to be its duct. Just posterior to 

 this gland is a lobed body projecting into the body cavity, bearing on 

 one of its surfaces long cilia which beat in the body cavity. No 

 further structures were observed in the living animal. 



The copulation was not observed. In a number of the females studied 

 at the time the males occurred were found spermatozoa, from one to 

 about a dozen in each female. All seen were within the body cavity 

 of the female and none in any portion of her genital tract. The 

 spermatozoa (PI. XX, fig. 33) are relatively huge lumbricoid cells, very 

 elongate, the more vibratile end of which appears to correspond to a 

 thick flagellum; they are exceedingly active and twist about within 

 the female, and within the sperm sac of the male, like animated cork- 

 screws. 



CoxcLUDixG Remarks. 



The family of the Flosculariidce includes the three genera Floscularia, 

 Stephanoceros and Apsilus. Leidy's description of Acydus is too incom- 

 plete to allow us to determine whether this form should be included 

 in the group also. Apsilus differs quite markedly from both Floscu- 

 laria and Stephanoceros (these two are very similar), but agrees with. 

 them in possessing an cesphageal tube, in the similar relations of the 

 nephridial and nervous systems, and in the great similarity of the young. 

 The immature females just hatched from the egg have the foot bearing 

 a tuft of ciha at its distal end. 



The general characteristics of the family are as follows, based upon 

 the few species already known anatomically : The anterior portion of the 

 trunk is expanded to form a capacious coronal cup, the free margin 

 of which is prolonged into lobes {Stephanoceros and most species of 

 Floscularia), or is without lobes {Apsilus, Floscularia edentata Collins 

 and pelagica Rousselet). The whole free margin of the corona con- 

 stitutes the boundary of a large mouth aperture. Cilia are absent 

 upon the corona in Apsilus. In Stephanoceros they are arranged 



