ANATOMICAL STRUCTURE OF KERRIA. 307 



The one pair of ciliated rosettes are found in somites x as 

 usual and are located exactly as in the genera Ocnero- 

 drilus and Gordiodrilus, free and independent of the 

 sperm-sacs. In shape the funnels are much more flattened 

 out, being very wide and with thick margin, almost plajie- 

 like, with the posterior part narrow and somewhat twisted. 



The genus Kerria must be considered to normally 

 possess only one pair of sperm ducts and ciliated rosettes, 

 though in one specimen I found two pair of ducts and 

 rosettes. The spermiducal pore opens on the median 

 papilla of the genital zone in somite xviii. The sperm 

 duct is rather wider than in Ocnerodrilus but extremely 

 delicate and easily ruptured and I could only ascertain its 

 position through sections; in dissecting it always became 

 torn. It is attached to the body-wall as usual and 

 is very wavy, in no instance, even for a short distance, 

 being straight, the folds doubling on themselves. The 

 duct is cylindrical throughout without any enlargement as 

 in some species of Ocnerodrilus and Pygmteodrilus. 

 Beddard's observation that the rosette of Kerria halofhila 

 is unusually large, is also applicable to the species de- 

 scribed here, but still the rosette does not by far stretch 

 across the whole somite. 



As already stated one specimen of Kerria McDonaldi 

 possessed two pairs of sperm ducts. The ducts in each 

 pair were entirely separated. The anterior rosette opened 

 in X, the posterior one in xi. The anterior sperm duct 

 opened adjoining the anterior prostate pore in xvii, while 

 the posterior sperm duct opened in the regular typical 

 pore in xviii. As the three other specimens contained 

 only one pair of sperm ducts and one pair of rosettes, 

 and as the specimen in question in all other particulars 

 resembled the typical form we may conclude that the two 

 ducts on either side must have been a retrograde develop- 



