BRITISH MAUINE TURBELLARIA. 517 



Species: — M.neapolitanum (copulatory organ funnel 

 shaped, the margin with a spur ; atrium very large) 



5. The anterior extremity converted into a tactile proboscis 

 provided with a (usually complex) musculature 



Family Proboscidae, 



I. Proboscis simple, with a sheath or muscle-cone. Short 

 muscle-bundles serve as retractors 



Sub- family Pseudorhynchiiiae, 

 a. Characters of sub-family Genus Pseudorhynchus. 

 Species: — P. 6i^cfM5 (hinder extremity bifid ; copu- 

 latory organ conical, with a screw-like ridge on its 

 outer surface). 



II. Proboscis provided with a sheath opening in front, a 

 muscle-cone, and four long retractors. 



Sub-family Acrorhynchinae. 

 a. Distinct seminal and granule vesicles, enclosed, how- 

 ever, in a common muscular, sheath. 



Genus Acrorhtnchus. 

 Species : — A. caledonicus (copulatory organ com- 

 posed of small chitinous spines). 

 h. Duct of granule-vesicle with special chitinous invest- 

 ment .... Genus Macrorhynchus. 

 Species: — M. Naegelii (copulatory organ tubular, 

 with a curved spur longer than the tube). M. 

 croceus (chitinous tube long, continued directly 

 into the " spur '') . M. helgolandicus (a chitinous 

 investment enveloping granule-vesicle and vas 

 deferens ; a poison-dart present). 

 c. Two genital pores, the female in front of the male 

 pore. Granule-vesicle with chitinous investment 



Genus Gyrator. 

 Species: — G. hermaphroditus (colourless; copula- 

 tory organ with a straight poison-dart). 



III. Proboscis small, behind the anterior end, its sheath 

 opening on the ventral surface. Granule- and seminal 



