lüO ACANrilUJdill.US BÜTTIKOI'liliU. 



regard of this fact the question may be put, as already 

 done by Beddard, in considering the systematic position of 

 Pleurochacta ^) — which resembles in many characters the 

 postclitelline Perichaeta . but lias intraclitelline generative 

 openings — if Perrier's system, how extremely convenient 

 it may be, is not too artificial and if he may base a clas- 

 sification on a glandular organ , which is often rather variable 

 in its extension , and not always distinctly limited by the 

 same segments. 



The length of the penial setae is 2 m.m. They are 

 slightly curved , slender , with their distal extremity swollen 

 and terminating in a sharply bent bifurcated point; this 

 point is envelopped by a membraneous prolongation of the 

 sides of the seta, like by a cap. Moreover these bristles 

 are covered nearly over one fourth of their length with 

 small triangular spines , strongly resembling the penial 

 setae of A. umjulatus Perr. At the innerside of the 17th 

 and 19th ring we find close to each bundle of penial 

 setae a slightly coiled , yellow-coloured , glandular tube , 

 the prostata. I have not been able to observe the vasa 

 deferentia , joining with these prostatic glands , notwith- 

 standing in the 13th segment distinct testes were present; 

 on the posterior side of the 1 2th mesentery , on both si- 

 des there is a flat lobed sac, containing incompletely de- 

 veloped spermatozoa. On the boundary-line of the 7th 

 and 8th, the 8th and 9th ring are situated the openings 

 of two pairs of copulatory pouches , corresponding to the 

 medial series of setae ; they are small oval vesicles , deeply 

 imbedded in the muscular coat. In the 1 4th , 1 5th and 

 16th segment the intestine is provided with a pair of re- 

 niform coeca, quite like in ^. *Sc/^%g/w; it is surprising that 

 these coeca , being present in both our specimens , have not 

 been observed by Perrier in the species described by him. On 

 each side of the pharynx in the 6th segment , extending into 



1) loc. cit. p. B02. 



Notes from tlie Ley den JMusenm , "Vol. "VI. 



