SIXTEN BOCK, TWO NEW COTYL. GEN. OF POLYCLADS. 17 



des alhus Hallez. which Hallez consequently fails to observe 

 when treatening Stylochoides very exhaustively. 



In this connection I may add some remarks to Hallez's 

 table (Hallez 1913, p. 41) for the five genera Stylochoides y 

 Cotylocera, Laidlawia, Enterogonimus and Leptoteredra. Hallez 

 states here that Laidlawia has »7 paires de brancbes intes- 

 tinales» wbilst Enterogonimus possesses 13. But Rudolf von 

 Ritter-Zahony says about the former (1907, p. 10) that »der 

 Hauptdarm gibt sieben breite, paarige Seitenäste und einen 

 unpaaren vorderen Ast ab». Enterogonimus according to 

 Hallez 1913, )t>presente treize paires de brancbes dont trois 

 se trouves en avant du pharynx, sept entré le pharynx et la 

 partie posterieuse de Ja ventouse, et trois en arriére de la 

 ventouse». The first three pairs belong with certainity to 

 the unpaired anterior gut-branch and I think that only the 

 se ven following pairs »entré le pharynx et la partie poste- 

 rieuse de la ventouse» correspond to what Zahony calls the 

 seven pairs of broad gut-branches of Laidlawia. In reality 

 there is no difference in the number of large paired gut- 

 branches from the main gut between Laidlawia and Entero- 

 gonimiis, 



The difference which Hallez finds between the number 

 of paired gut-branches of his Stylochoides alhus and Zahonys 

 Cotylocera michcelseni must, I think, be attributed just to the 

 different way of counting these pairs. Zahony only counted 

 the brancbes leaving the broad main gut (Hauptdarm) while 

 Hallez counted all the brancbes diverging from the median 

 intestinal canal, including the so-called anterior unpaired gut- 

 branch. If then we read Hallez's table (Hallez 1913, p. 41) 

 for Stylochoides and Cotylocera with common sense we shall 

 find that the differences between these genera in reality do 

 not exist or at least the table has no value at all in sepa- 

 rating them. Thus we shall see in Hallez's table how the 

 two genera agree in having two tentacles (but it is not 

 mentioned that these tentacles in both cases are nuchal 

 which is, indeed, of considerable interest, as no other cotylean 

 polyclad possesses such tentacles, they being otherwise mar- 

 ginal) further »ventouse puissante», »gaine pharyngienne tres 

 longue», »pas de vésicule séminale». 



According to the table they disagree in the number of 

 gut-branches, which can be attributed to the different way 



Arkiv för zoolorfi. Bd 14. N:o 13. 2 



