104 



MR. F. F. LAIDIiAW ON POLYCLADS 



[May 26, 



rows extending forward from over the brain. They are mostly of 

 small size, but immediately over the brain there are on either side 

 some half-a-dozen eyes of a much greater size than the rest. 



Text-fia-. 4. 



Disparoplana dubia, sp. nov. X 4 circ. 



Unfortunately the solitary specimen is not in a veiy satisfactory 

 state of preservation. The epidermis has almost completely 

 disappeared, and the body is much distended with vipe eggs, so 

 that the characters of the gut are difficult to determine. The 

 phaiynx is folded and of the usual Acotylean type. The brain is 

 protected by a sheath of unusual toughness. 



Genital Organs. 



Male afparaUis. — The terminal parts consist of a cylindrical 

 penis lined with short chitinous spines, of a small prostate gland, 

 and of a muscular vesicula seminalis (PI. IX. fig. 2). The resem- 

 blance to the corresponding organs in Planocera or Paraplanocera 

 is very close. The male aperture is very small and opens into a 

 narrow tube which rvms forwards and a little upwards. The cells 

 lining it give off a granular secretion. After a course of about 

 1 mm. this passage widens out to become the lumen of the penis. 

 This oi'gan is proportionately longer than in Planocera and a 

 little coiled ; but shorter than in Paraplanocera. Its walls are 

 not very stout, and the muscle-fibres which form them are con- 

 tinuous with those that surround the prostate. The spines lining 

 the lumen bear a close resemblance to those of Planocera ; but 

 the diameter of the penis is relatively less. The prostate is small, 

 but similar to that of Planocera. Its duct ig^. joined by the ductus 

 ejaculatorius running to the penis from the relatively large 

 vesicula seminalis which lies in front of the prostate and receives 



