SIXTEN BOCK, TWO NEW COTYL. GEN. OF POLYCLADS. 15 



points out (1913, p. 39) but the ovaries. I have related this 

 because Hallez's correcting remarks make it very probable 

 that Aceros stylostomoides, described in August 1907 by J. F. 

 Gemmill and R. T. Leiper, from South Orkney Islands is 

 identical with Leptoteredra {Aceros) maculata (Hallez 1905) 

 Hallez 1913 [which was described anatomically first in July 

 1907] from Graham Land. Both were obtained at about the 

 same depth, 9 — 10 fms. and 20 metres respectively. 



Like Leptoteredra maculata the Aceros stylostomoides has a 

 length of 3 — 4 mm. and lacks tentacles. The position of the 

 openings agrees well in both. The number of cerebral eyes 

 is in ^. stylostomoides 2X 15, in maculata 2X 14 — 15; tentacular 

 eyes 2X8 — 9 and 11-- 12 respectively on the ventral side. 

 The pharynx is in both short and tubular. The main gut 

 of both is spacious with five pairs of ramifying unanastom- 

 osing gut-branches and is as an exceptional feature provided 

 with a dorsal porus. The genital organs of stylostomoides 

 also agree well with those of Lep^o^ere^ira.* The penis is large, 

 of an elongated, pyriform shape, and has no stylet. The 

 last point is not expressly stated by the British authors, 

 but can be seen in the figures given by them (1. c, Plate, 

 fig. 1). There are in stylostomoides »two uteri into which 

 the oviducts open. No uterine glands. The ovaries are 

 found throughout the lateral parts of the body». Nothing 

 is said about the number of the ovaries. But the following 

 sentences bear an indication that a similar condition prevails 

 in the specimens of the British authors as Hallez describes 

 as the double function of the ovaries. Gemmill and Leiper 

 write: »Many of the ovarian tubes contain yolklike material 

 which seems to be derived from the transformation of cellulär 

 elements within their walls. This arrangement seems to 

 replace the special uterine glands described as occurring in 

 Aceros inconspicuus and certain other Euryleptidce>K 



The only differences I am abie to make out from com- 

 paring the schematic figures given is that stylostomoides has 

 the unpaired anterior gut-branch passing the brain while in 

 maculata it does not reach the brain, and that in the former 

 the sucker is large and in the latter it is rather small. In 

 the description of A. stylostomoides we read further that the 

 specimens »are of a warm brown tint, mottled on the dorsal 

 surface by a coarse, darkly pigmented network, the strands 



