26 



IVAR ARWIDSSON. SYSTEMATIC NOTES ON SOME MALDANIDS. 



the contrary; as a matter of fact the fractures showed evidently that the pieces had 

 not been continuous. Thus Mc Intosh seems not to have had before him any material 

 which can throw light on the number of setigerous segments in the main species. 



When to this is added that there exists at the Riksmuseum in Stockholm a smaller 

 specimen of the main species from East Greenland, Frans Joseph Fiord, which has a 

 rather distinct notch between the cephalic borders posteriorly, Nolte's variety seems 

 still more questionable; in this point, however, he can of course support bis statement 

 by opposing it to my earlier unrestricted one that these borders at their posterior con- 

 nection are only slightly sinuated. Still I am of the opinion that, on account of the 

 material at hand, the var. borealis Nolte can be maintained. The main species seems 

 moreover to be more or less arctic. The diagnosis of var. borealis Nolte would then be 

 as follows: 



Distinct notch between the cephalic borders posteriorly. Ocelli present. 18 seti- 

 gerous segments [not improbably as in the main species]. Maximum size considerably 

 less than in the main species. The ventral cirrus long and fine; its length is (2 7 2 — ) 3 



Text-fig. 11. Praxillella gracilis var. 



borealis. — Uncinus (first from above) 



from the 2 nd setigerous segment. 



590: 1. Trieste. 



Text-fig. 12. Praxillella gracilis var. Text-fig. 13. Praxillella gracilis var. bo- 



borealis. — Uncinus (second from above) realis. — Uncinus (second from above) 



from the 3 rd setigerous seg ment. 440: 1. from the l st setigerous segment. 450: 1. 



Firth of Clyde. Firth of Clyde. 



times as great as the diameter of the posterior end within the anal cirri. The uncini of 

 the (l st — ) 2 nd — 3 rd setigerous segments with the l sfc tooth considerably longer than 

 in the main species. 



The material at my disposal is as follows. 



Firth of Clyde: Between L. Cumbrae and Millport, mud, 12 / 9 1912. 1 specimen 

 in five parts, which were placed by Dr. Potts together with other maldanids in a tube 

 labelled: »Whole specimens. » It is therefore most probable that this specimen is comp- 

 lete, and if so it has 18 setigerous segments. The number of the anal cirri is 18 and the 

 size of the specimen is about 35 X 12 mm. — Do., Sept. 1912. 6 anterior ends, of which 

 at least 2 out of 3 investigated have sparse ocelli between the anterior part of the lateral 

 borders of the head and the mouth (ef. text-fig. 9). Behind the finger-like cephalic 

 point there are on each side 2 and outside these 5—6 ocelli. Another specimen has only 

 1 middle ocellus (somewhat to the left), but 10—15 on each side of this. The proboscis 

 papillae resemble those of the main species, with regard also to the number of the rows. 

 There are about 37 papillae on the distal edge of the proboscis and if the next row is 

 also included the number increases to about 60. The anal cirri of the 4 posterior ends 

 number 16, 17, 18 and 21 respectively and are generally largest and most sparse towards 



