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front and behind, greatest height about equal to 3 / 5 of the length, dorsal margin 

 very slightly arched and somewhat angularly bent in the ocular region, ventral 

 margin indistinctly sinuated in front and rather bowed hehind, anterior extremity 

 obliquely rounded, posterior produced above the middle to a blunt prominence 

 defined dorsally by a slight sinus; seen dorsally, broadly ovate or cordiform 

 in outline, with the greatest width behind and almost attaining 2 /3 of the length, 

 side-edges gradually expanding backwards and abruptly bent near the posterior 

 part of the shell, anterior extremity obtusely pointed, posterior abruptly con- 

 tracted to a conical prominence; end-view short pyramidal. Valves of some- 

 what firmer consistency than in most of the other species, though rather 

 pellucid, each exhibiting a well marked obtuse expansion flanking the side 

 below and terminating behind in a rounded corner; surface otherwise smooth 

 and marked with small rounded pits more conspicuous in the lower part of 

 the shell, posterior edge of each valve fringed below with a regular row of 

 small denticles. Eyes distinctly visible in the living animal, though rather 

 poorly developed, with light pigment. Anterior antennae with the terminal 

 part considerably exceeding in length the basal one, last joint very narrow 

 and carrying on the tip a bunch of rather long and thin bristles. Posterior 

 antennae with the 1st joint of the terminal part fully twice as long as broad, 

 middle joint much narrower, last joint very small. Legs moderately slender, 

 last pair with the 1st joint of the terminal part shorter than the other 2 

 combined. 



Male very like the female both in size and in the general shape of the 

 shell. Copulative appendages with the terminal part considerably produced, 

 lanceolate in form. 



Colour of shell light yellowish white, variagated with a few small reddish 

 specks dorsally. 



Length of adult female 0.90 mm. 



Remarks. The above-described form ought to be regarded as the type 

 of the present genus, being that first named of the species originally recorded. 

 It is easily recognised from the other known species by the short and com- 

 pact shape of the shell and by the presence of distinct, though rather poorly 

 developed eyes. 



Occurrence. \ first met with this form in the Hallandspol near Dr0bak, 

 where some few specimens were found at a depth of about 10 fathoms, muddy 

 bottom, and I have subsequently also taken it in several other places, both 

 on the south and west coasts of Norway in moderate depths. 



Distribution. British Isles, Spitzbergen, Gulf of St. Lawrence. 



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