157 



curved sensory appendages, 7th joint very elongated and apparently formed by 

 the coalescence of 5 articulations. Oral parts, as in the male of Pseudocalanus, 

 much reduced. Last right leg scarcely l / ?J as long as the left, terminal joint 

 simple, rounded. 



Colour. Body in both sexes highly pellucid and almost colourless. 



Length of adult female scarcely exceeding 0.70 mm., that of male about 

 the same. 



Remarks. This dwarf Calanoid, perhaps the smallest of all hitherto 

 known forms, is closely allied to the polar species, M. pygmceus, though differing 

 conspicuously in the much shorter anterior antennse, as also in the structure of 

 the natatory legs, but more especially in the peculiar development of the apical 

 spine of the outer ramus. It may here be remarked that the male specimen 

 figured on PI. XXII of my Account of the Crustacea of the Norwegian North 

 Polar Expedition, and described as the male of Spinocalanus longicornis, most 

 certainly does not belong to that form, but to Microcalanus pygmceus, which is 

 proved by its great similarity to the male of the present species. 



Occurrence. Owing to its small size and inconspicuous colouring, this 

 form had previously quite escaped my attention, though in reality it seems to be 

 rather common, at any rate off the west coast of Norway. During a 2 months' 

 stay last summer in that part of the country, I found this Calanoid rather abund- 

 antly in 3 different places, viz., at Christiansund, Aalesund, and in the Storfjord, 

 farther inland than the last-mentioned town. In all these places, however, it only 

 occurred in depths of more than 150 fathoms; and it thus appears to be a true 

 deepwater form. The same species was also found in 2 plankton-samples kindly 

 sent to me by Mr. Nordgaard, both taken from great depths, the one in the Herlo 

 Fjord, the other in the Oster Fjord, near Bergen. Finally, some few more or 

 less defective specimens of a Microcalanus (perhaps more properly referable to the 

 polar species) were picked out of a plankton-sample taken during the cruise of 

 the "Michael Sars" in the open sea between Jan Mayen and Finmark. 



Page 22: Spinocalanus abyssalis, Giesbrecht. 



(See PL XII & Suppl. PI. Ill, fig. 2). 

 Spinocalanus abyssalis, Giesbrecht, Fauna & Fl. Golfes Neapel. Pelagische Copepoden, p. 209, 



PI. 13, figs. 4248, PI. 36, fig. 49. 



Syn: Spinocalanus longicornis, G. 0. Sars. 



(For the description of the female, see p. 22). 



Description of Male. General appearance very different from that of 

 the female. Anterior division of body oblong oval in form, both extremities, 



