NEW SPECIES OF OCNERODRILUS. 245 



absence, relative size or form, of the sperm-sacs in somites 

 ix and xii appear to afford good species characters. In 

 OcnerGdrthis occidentalis they are entirely wanting in 

 somites ix and xii. In the other species described here 

 as new these sperm-sacs are present, their lobation at 

 least in its general traits, being characteristic of the 

 species. 



Sferm duct and ciliated rosette. There are two pairs of 

 ciliated rosettes, one pair in somite x and one pair in xi, 

 corresponding to the testes (fig. i8). The rosettes are 

 placed behind and close to the testes, and their structure 

 offers nothing unusual. They resemble each other in all 

 the species, are very large and delicate, spreading over 

 the lower parts of the hearts, but free of the septa. The 

 inner cells are large rectangular, with large oval nuclei 

 and long cilia. The sperm ducts pass backwards and 

 unite imperfectly with each other in somite xi or xii, 

 and continue from that on as one duct to somite xvii, 

 where are situated the male or spermiducal papill^E, and 

 in which also opens the prostate gland (or atrium). The 

 sperm ducts are closely following the body wall, do not 

 run straight, but in a wavy, snake-like way, but are not 

 coiled. (In fig. i they are represented as straight 

 in order to make the fig, clearer.) The male pa- 

 pillae, of which there is one pair, occupy the same place 

 as the inner setae in the respective somites. There 

 is only one seta left, the other, the outer one, being 

 abortive. The single remaining seta is not differentiated. 

 In three of the species, the penial sette are wanting, while 

 in Ocnerodrilus occidentalis and other species they are 

 either both present or one is wanting. The sperm ducts 

 which in some species are enlarged in the vicinity of the 

 male pore, are in this species of even width throughout 

 their length. The ducts are only imperfectly joined. 



