356 HELEN L. M. PIXELL ON 



it was only with considerable difficulty that any perfect ones were obtained. The 

 collar has small dorsal lobes, and becomes gradually higher towards the mid-ventral 

 line, where there is a deep fissure. 



The ventral gland-shields are very distinct, separated by deep segmental fissures, 

 and divided in the abdominal region by a deep and narrow faecal groove, which crosses 

 obliquely to the right on reaching the thorax, and is continued as a very shallow groove 

 alons the mid-dorsal surface. 



No pigment spots could be made out at the posterior end, and there is practically 

 no colour in the preserved animals ; only faint transverse markings could be made 

 out on the branchiae. In all other points there seems to be exact similarity with 

 Gravier's widely distributed sjDecies. At the same time, I cannot help thinking that 

 the variation, which he points out (8, p. 145) as existing in two of the characteristics 

 on which he has based his species in differentiating it from P. neglecta Malmgren and 

 P. incerta Lang, tends to do away with its distinctness. 



Genus Potamis Ehlers, 1887(4, p. 278). 



Generic characteristics : — 



1. Thoracic tori double rows : avicular crotchets with long bases and pennoned 



setse respectively. 



2. Abdominal tori single rows of avicular crotchets. 



3. Collar present. 



4. Thoracic setae of two forms — superior ones with rather wide blades, inferior 



sub-spathulate. 



5. Abdominal setae of two kinds — long narrow-bladed ones and short forms 



with wider blades (lanceolate) (fig. 7,f). 



6. Gill bases sub-involute. Branchiae without ocelli. 



Potamis scotise n. sp. 



1. Collar with high ventro- lateral lobes and deeply divided in the middle line. 



2. Setae and crotchets of characteristic shapes (fig. 7, a-h), diff'ering in many 



ways from those of P. spathiferiis Ehlers. 



3. Ventral gland-shields quite distinct, divided in the abdominal region by a 



wide and shallow faecal groove. 



Locality. — One specimen, without its tube, taken in the trawl at Station 417, 

 lat. 71° 22' S., long. 16° 34' W., from a depth of 1410 fathoms. 



Total length 133 mm., of which 63 mm. is made up by the branchial crown, 10 mm. 

 by the thorax, and 60 mm. by the abdomen. Greatest width 5 mm. 



After being preserved in dilute formalin the general colour of the specimen (is 

 greenish-brown. The segments are clearly marked off from one another by inter- 

 segmental constrictions, and the setae protrude to a considerable distance. 



