92 



tcrwards recognized to be nepliridiii and not salivary glands opening 

 into the oesophagus, the sixth and seventh segments contain two series 

 of glands: 1) two glands composed of numerous spherical acini the 

 ductules of which unite and open into the oeso])hagus close to the sep- 

 tum whicli separates segments G and 7. 2) Two py rifornì glands in 

 the 0"" segment opening into the oesophagus at the same point as the 

 last. My own investigations into the anatomy of this species lead me 

 to differ in certain particulars form M. Pcrrier. The »glandes en 

 grappes« are formed as Perrier states by numerous acini connected 

 with a branching system of ductules which unite to form a thin walled 

 duct of considerable calibre. The acini are comi)oscd of very small 

 nucleated cells , and frequently appeared to be solid ; in others how- 

 ever a lumen could be observed. 



The acini are abundantly supplied with bloodvessels. 1 find that 

 there are three pairs of groups of these acini occupying, respectively 

 segments .'>, 6 and 7. These salivary glands thus exhibit a me- 

 tamerie arrangement. The »pyriform glands« of Perrier seem to 

 me to be the collecting tube which receives the ductules from the se- 

 veral groups of acini, and, passing forwards, opens into the hinder re- 

 gion of the pharynx. 



In another species of Perichaeta — P. aspergillum — the same 

 glands are present. 



These salivary glands are, in my opinion, to be regar- 

 ded as the homologues of the septal glands of the En- 

 chytraeidae and Lumbriculidae. In Anachaeta (Enchy traeidae) 

 and in PhrcatotJirix (Lumbriculidae) there are, according to the 

 figures and desciiptions of Vejdovsky 2^ three or four pairs of these 

 glands connected by a common longitudinal duct on each side, which 

 opens into the pharynx. In their metamerie arrangement , and in the 

 common longitudinal duct they agree with Perichaeta ; the only diffe- 

 rence is that there is but a single acinus on each side in each segment 

 in these lower Oligochaeta, while in Perichaeta the acini are numerous. 

 There is thus a close correspondence between Perichaeta and certain 

 »Limicolaeu in the structure of the salivary glands; this fact lends addi- 

 tional support to the contention that it is impossible to divide the Oii- 

 gochaeta into two groups »Li?nicoIac(i and nToTicohieu. 



(2) Capsulogcnous glands. In three species of Perichaeta, 

 viz. P. Iloulleti, P. aspergillum and P. mirabilis there are a number of 

 small glands which may possibly represent the capsulogenous'glands 



2 System und Morphologic der Oligochaeten. PI. VII. Fig. 1. PI. XI. 

 Fig. 17. 



