BRITISH MARINE TURBELLARIA. 463 



be absent. A remarkable variety is figured iu PL XL, fig. 15, 

 The ovaries, and between them the large spermotheca, 

 lie posteriorly. One egg-capsule was present in many indivi- 

 duals at Plymouth in September. In November no adults 

 could be found. They had probably died off. 



Habitat. — Similar to Acrorhynchus caledonicus. The 

 two are, however, only occasionally found together. Plymouth 

 Sound (F. W. G.) -, Millport ( v. Graff, '' Ich selbst habe in 

 Millport niemals grossere Exemplare gesehen als Claparede^s," 

 p. 323, 'Monogr.'). 



Distribution. — This is the commonest Ehabdocoele at Naples. 

 Lesina, Messina, Trieste (v. Graff), Sebastopol (Uljanin), 

 Black Sea (Czerniavsky), Madeira (Langerhans, MSS.). 



23. Macrorhynchus croceus (Fabricius, 9). 



Length 1*5 mm. Body reddish, swollen posteriorly, 

 pointed in front, where it is nearly white. Proboscis very 

 powerfully developed. Of the parts composing the genital 

 apparatus, the most diagnostic is the copulatory organ. At its 

 proximal cylindrical end it receives the secretions of the 

 vesicula seminalis and granule-reservoir, which are contained 

 in an elongate sac strengthened by spirally-arranged muscles. 

 The distal portion is spirally twisted, and consists of two 

 canals, each containing a part of the continuation of the 

 proximal single cavity. The upper edge of this spiral is 

 " toothed.'^ The egg-capsule is stalked. Several points, such 

 as the relations of the germ- and yolk-glands and the presence 

 of a spermotheca, are not yet satisfactorily determined. 



Habitat. — Among Fucus and Laminaria below the surface 

 of the sea. Millport (v. Graff) ; Plymouth (F. W. G.). 



Distribution. — Apparently abundant in the northern seas. 

 West coast of Greenland (Levensen) and of Norway (Jensen), 

 Faroe Islands (Schmidt), Denmark (Oersted), Wimmereux 

 (Hallez). 



