ON A NEW SPECIES OF PHTMOSOMA. 173 



and covering these again is the layer of flat peritoneal epi- 

 thelium. 



The very curious mode by which the glandular cells of the 

 nephridium in Ph. varians excrete their waste products^ by 

 casting off vesicles into the lumen of the organ, is repeated in 

 this species. These vesicles contain granules. Their method 

 of formation and of breaking ofi' from the free end of the 

 secreting cell is paralleled by the secreting cells which line the 

 mammary glands of Mammalia^ or by the cells which give 

 rise to the secretion of the liver in Astacus. 



The generative organs consist of a band of modified peri- 

 toneal epithelium which lies at the base of the retractor 

 muscles. The generative products split off into the peritoneal 

 cavity. 



Part III. 

 A Synopsis of the Genus Phymosoma. 



In the admirable systematic monograph'^ on the Sipunculidsej 

 in which Prof. Selenka, with the assistance of Dr. de Man and 

 Dr. BiiloWj published the results of their work on the Gephyrea 

 collected by Prof. Semper in the Philippine ArchipelagOj a 

 synoptical table of the genus Phymosoma, which included at 

 that time eighteen species, is published. Since 1883, the year 

 of the publication of the above-mentioned work, nine new 

 species have been added to the genns. Eight of these are due 

 to the energy of Dr. Sluiter,^ who has done so much to increase 

 our knowledge of the marine fauna of the Malay Archipelago. 

 The ninth was found by Prof. Weldon in the Bahamas. It will 

 thus be seen that since the publication of Selenka's synopsis 

 the number of described species of Phy mos omahas increased 

 by half the original. I have, therefore, prepared the fol- 

 lowing table, which is largely founded on Selenka's, but 

 which includes those new species of the genus which have been 

 described since the publication of his monograph. 



' In a note in my previous paper on Ph. varians this work was inad- 

 vertently attributed to Prof. Spengel. 



" ' Beitrage zu der Kenntniss der Gephyreen aus dem Malayischen Archipel,' 

 von Dr. C. Ph. Sluiter. 



