CONTRIBUTION TO KNOWLEDGE OP EHABDOPLEURA. 633 



movement of the polypide due to the cilia, and possibly to the 

 very slight undulating movements of the buccal-shield. 



Testis.— No reproductive organs were found, either by 

 Sars or by Allman, in Rhabdopleura. Mcintosh found very 

 large ova in Cephalodiscus, but no testis. I have found a well- 

 developed testis in Rhabdopleura, Its position, shown in 

 PI. XL, fig. 7, is remarkable, since it projects from the 

 surface of the body, stretching the delicate integument of the 

 abdomen. It lies parallel to the intestine on the right side, 

 opens near the anus, and in some cases reaches back beyond 

 the rounded end of the abdomen, projecting as a lobe beyond. 

 It was present in only a few of the polypides examined by me 

 at Lervik in August; and I infer that they were exceptional 

 specimens, in which the testis had ripened late, or for other 

 reasons had not discharged itself during the breeding season, 

 which probably was just over when I began my studies. 

 Accordingly, I should urge anyone who may wish to attempt 

 to obtain a knowledge of the embryology of Rhabdopleura to 

 commence dredging operations in the middle of June.^ 



The testis of Rhabdopleura has the form ofa much elongated 

 sac, ending blindly at one end and opening by the other to the 

 exterior by a special pore. At the blind end some sperm 

 mother-cells were seen, but the greater part of the sac, in all 

 cases, was densely packed with ripe spermatozoa, which could 

 be discharged by pressure at the genital pore, and then exhibited 

 active movements (PI. XL, fig. 8). 



This is a remarkable form of testis, and unlike anything known 

 in the ordinary Polyzoa. The sac is possibly to be regarded 

 as a hernia-like protrusion of the body wall. The position of 

 the orifice corresponds with that of the genital ducts of Pho- 

 ronis, but these are modified nephridia. On the contrary, 



^ I may mention that last year, I employed Rasmus Lilljeboo of Lervik, 

 who had been one of my boatmen in the previous year, to dredge for Ehabdo= 

 pleura in May, June, and July, in order, if possible, to ascertain its breeding 

 season, in case I should be able to go again myself in some future year to 

 Lervik. He did not succeed in obtaining a single specimen of Rhabdopleura, 

 either with or without sexual organs. 



