602 M. Kowalewski: 



The author finisbes the paper almost in the following words: 

 There can be no doubt tbat tbe genus Aulodrilus belongs to 

 tbe family of Tubificidae. To tbe typic members of this family, 

 possessing reproductive organs in segments X and XI, it is 

 related by such a form as IJyodrilus hedoti Piguet 1913 with the 

 sanie organs in segments VIII and IX. But it offers also some 

 relation to the family of the Naididae in which the organs in ques- 

 tion occupy segments V and VI, so that they are situated only 

 one sefjmeut more forwards than in the genus Aulodrilus. This con- 

 nexion is supported furthermore by the existence of rudimentary 

 testes in segment V, in which segment in the last cited family the 

 normal testes lie. and also by the existence of a respiratory organ, 

 resembling topographically (not anatomically) and histologically 

 (stellate cells) the branchial organ in the genus Dero. Taking 

 thèse facts for his foundation the author considers the genus Aulo- 

 drilus as an intermediate form between the Tubificidae and the 

 Naididae. 



Explanation of plates. 



Ail the figures — excepting' 3, 23, 26, 39 — 48, 48 — are inade with the 

 help of a caméra lucida. 



Référence letters : 



at. — atrium; c. — cor; M. — cellulae chloragogeneae; cl. — clitellum; 

 d. ej. — ductus ejaculatorius : ffl. d. — glandulae dermales; gl. s. g. — glandu- 

 lae setae genitalis ; i. — iutestinuin; l. l. — linea lateralis; m. c. — museuli 

 circnlares; m. d. v. — museuli dorso-ventrales; m. l. — museuli longitudinales; 

 m. spth. — museuli spermathecales; n. — truncus nervosus; ov. — ovum; ovr. — 

 ovarium; p. — pénis; pr. — prostata ; j;. sjjfh. — porus spermathecae; s. d. — 

 setae dorsales; s. g. — setae génitales; s. s. — saceus spermaticus ; s. s. g. — 

 sacculus setae genitalis; sp. — sperma in evolutione ; sj)th. — spermatheca; s. v. — 

 setae ventrales; t. — testiculi, w. — ntricnlus setae genitalis; v. c. — vasa cir- 

 cularia (commissuralia) ; v. d. — vas dorsale; v. def. — vas deferens; v. i. — 

 vasa intestinalia; r. sp)th.. — vestibulum spermathecae; v. v. — vas ventrale; 

 F — IX — number of the segment. 



Plate .47. 

 Aulodrilus limnobius Bretscher 1899. 



Pig. 1 and 2. — Maie reproductive organs, side- and ventral view. X 195. 

 Fig. 3. — Prostata and a part of atrium, from a living, somewhat compres- 

 sed spécimen. 



Fig. 4. — Ventral view of sexual segments, X 9^- 



