14 ARKIV FÖR ZOOLOGI. BAND 14. N:0 13. 



as they also deviate in other respects from the Euryleptidce, 

 their nearest relatives. 



From this discussion the conclusion can be drawn that 

 Chronwplana is certainly in some Avay related to the Pseudo- 

 cerid-Euryleptidean series but the differences in the male 

 apparatus are so big that they do not allow us to include 

 it in either of these families, all the more as just with re- 

 gard to the generative organs the Pseudoceridce and Euryleptidce 

 show the greatest conformity. 



It still remains to adopt a view concerning the Cotyleans 

 described since Lang*s monograph was published. Most of 

 them have without any difficulties at all been properly in- 

 cluded in Lang's families. Only the following genera need 

 any further discussion :Penc6?is(LAiDLAW, 1902 and Meixner 

 1907), Diposthus (Woodworth, 1898) and the four genera 

 Styloclioides (Hallez, 1907; see also Bock, J913, pag 276), 

 Laidlawia (Herzig 1905 and Zahony, 1907), Enterogonimus 

 Hallez 1911 (Hallez, 1913) and Le^^^o^crerfm (Hallez, 1913), 

 by Hallez 1913 included in his sub-family Laidlaiviince under 

 the family Euryleptidce. 



I find it necessary to treat Hallez's genera a t some length, 

 as my views may be of some value for future investigators 

 of the antarctic or subantarotic polyclad fauna to which they 

 all belong, or at least to call attention to certain facts. 



In 1905 Hallez described an Aceros maculatus n. sp. from 

 the Antarctic. This species is again treated by him in 1907, 

 where a more detailed account is given. In a new memoir 

 on the antarctic polyclads (1913) he established a special 

 genus for it, Lepioteredra. There he also corrects some mis- 

 takes made in his previous anatomical description. He bad 

 stated (1907, p. 12) that »Tappareil copulateur mäle ne 

 mérite aucune mention spéciale. Par ses connexions comme 

 par sa structure, il est conforme å celui de Tespéce médi- 

 terranéenne». According to Lang the Mediterranean Aceros 

 mconspicuus possesses a penis stylet. Lang does not express 

 this plainly, but in the first place he says that the male 

 copulatory organ agrees with that of Stylostomum and sec- 

 ondly a stylet of this type can be traced in a schematic 

 figure. In 1913 Hallez mentions that his species in question 

 has a «>pénis sans stylet». What Hallez in 1907 describes 

 as eleven »vésicules utérines» is nothing else, as he himself 



