6 IVAR ARWIDSSON, SYSTEMATIC NOTES ON SOME MALDANIDS. 



Nicomachinae. 



In 1915 Mc Intosh (31, p. 306) made the following statement: »It seems doubtful 

 if Arwidsson's species — Nicomache minor, Nicomache trispinata var., Nicomache 

 quadrispinata — are other than varieties, for in the common form four spines some- 

 times occur, and so with eyes». Apart from the fact that Nic. maculata, with which 

 Mc Intosh compares the three species mentioned, was not described until 1911 and 

 the others as early as 1907, all by me, it seems snrprising that Mc Intosh can put for- 

 ward the above statement without discussing the question in more detail. Nicomache 

 minor and Nicomache maculata are referred by me to the sub-genus Nicomache, N. tri- 

 spinata and N. quadrispinata to the sub-genus Loxochona. N. minor is characterized, 

 inter alia, by 23 setigerous segments, anal cirri of different length, and up to 5 teeth on 

 the uncini. N. maculata has 22 setigerous segments, equally long anal cirri and up to 7 

 teeth on the uncini. If, disregarding my division of the genus Nicomache into two sub- 

 genera, we bring N. trispinata and A T . quadrispinata into proximity with the two other 

 species, we are immediately struck by the difficulty, among others, that the two species 

 just mentioned are without nephridia in the 6 th setigerous segment; in addition it is to 

 be noted that N. quadrispinata is distinguished by achaetous uncini of such an appear- 

 ance that at present it is possible merely by the uncini to distinguish the species from 

 all previously known Maldanids! It is of course quite desirable that well-grounded 

 remarks should be put forward, but one must protest against the work of specialists be- 

 ing rejected on such vague grounds as has evidently been the case here. 



Nicomache (Nicomache) lumbricalis (Fabricius), var. borealis Arwidsson. 

 1907. Nicomache lumbricalis var. borealis Arwidsson (24, p. 94). 



An anterior end, scarcely of average size, from the North sea 55°43'45" N, C 30' 

 W, 75 m. (S. S. Huxley, July 13 th , 1906) and labelled »Nicomache lumbricalis», be- 

 longs to the variety just mentioned, to judge from the presence of glands already be- 

 hind the nephridia-openings of the 7 th setigerous segment (ef. 24, pp. 88 and 97); besides 

 there is no reason here to expect the main species, which is chiefly aretic. 



The tube consists mainly of quarvZ granules. 



Mc Intosh says iii his large monograph on the British marine annelids (31, p. 

 305): »Nicomache lumbricalis, which has sometimes been confounded with the present 

 species [N. maculata], is an aretic form which does not appear to extend to British seas. » 

 It is certainly true that the main species of N. lumbricalis is chiefly aretic, as mentioned, 

 but its nearly related var. borealis, distinguished by me in 1907, is found, for instance, 

 from Öresund to Trondhjem Fjord and farther in the North Sea, where Michaelsen 

 (17; in addition M. had N. maculata before him) mentions it from the southern part 

 and Nolte (30, p. 31) from, inter alia, 4 localities north of the Dogger Bank (65 — 95 

 m.). It seems to me therefore not improbable that a number of earlier statements as 

 to the occurrence of N. lumbricalis in British waters may be correct, provided the species 



