4 IVAR ARVIDSSON, SYSTEMATIC NOTES ON SOME MALDANIDS. 



In describing capillary setae I still use the expression »börder», although from 

 Nolte's (30) and Söderström's (35) investigations we know that these »borders» 

 are, at least in the majority of cases, only the optical section of the more or less hyaline 

 manfcle of the setae. I have not had an opportunity to investigate these setae carefully 

 and the nse of this expression in pure descriptions seems to me convenient or at least 

 permissible. 



Liiiiibriclymeninae, 



Praxillura sp. ? 



As representatives of this genus are on the whole not often met with or at any råte 

 seldom noted in the literature, the following find may be published here. In the Firth 

 of Clyde, near the shore of Great Cumbrae (sandy beach) was captured by Dr. Potts 

 in July 1910 an individual of which the 61 mm. long posterior part, comprising about 

 50 segments, is now in the collection. About the 10 last segments have not yet got ex- 

 teriör setae. The tube has a sparse layer of granules mainly of quartz. 



Notoproctus paciflcus (Moore). 



(Pl. 1, figs. 1—4.) 



1906. Lximbriclymene pacifica Moore (23, p. 246). 



1911. Notoproctus pacificus (Moore) Arwidsson (27, p. 8). 



This species, characterized by its anterior part being strongly coloured on the 

 upper side with brighb bands surrounding the parapodia, by slightly arched nuchal 

 organs, 19 setigerous segments (1 — 4 of which have spines), and two posterior achaetous 

 segments, is represented in the collection by a complete specimen, which seems in all 

 essentials to agree with Moore's description. The brown colour is thus (see fig. 1) dis- 

 tributed in the way indicated by him, but there are in addition 4 distinct more or less 

 extensive patches on the upper side of the head, 2 of which are placed laterally quite 

 at the edge of the head (fig. 2). This design of the head, like other characters, differen- 

 tiates the species rather decidedly from Notoproctus oculatus Arwidsson (24, fig. 34). 

 Ocelli are not observed with certainty, but there are possibly weak ones under the edge 

 of the anterior side of the head in a line with the träns ver se anterior patch. The brown 

 colour design extends further to the 5 th setigerous segment inclusive, where, however, 

 it is påle, especially behind the parapodia. The mosb strongly coloured band is situated 

 dorsally just behind the head, i. e. on the buccal segment. The inner shank in the nuchal 

 organs, which are rather unlike those in N. oculatus Arwidsson, is short and but a little 

 curved (ef. fig. 2). The diagnosis of the genus Notoproctus (24, p. 51) which states that 

 the nuchal organs form uniform, regular arches, is thus too narrow. 19 setigerous seg- 

 ments, the four first of which have single spines, and 2 distinct posterior segments without 

 setae also characberize this specimen, which is about 70 mm. long; figs. 3 — 4 show these 



