77 



remarkably extant on right side. Genital segment slightly asymmetrical and 

 considerably dilated in the middle, lateral edges finely ciliated, ventral face with 

 a recurved spiniform process immediately in front of the genital orifice. The 2 

 succeeding segments of about equal size and considerably smaller than the genital 

 segment. Caudal rami sublinear in form, about 3 times as long as they are 

 broad, apical setae more elongated than in C. typicus. Anterior antennae, when 

 reflexed, reaching to the end of the caudal rami, none of the articulations with 

 dentiform projections. Legs comparatively more slender than in the type species, 

 with the terminal spine of outer ramus more coarsely denticulate. Last pair of 

 legs with the unguiform process much shorter than in that species. 



Male still more slender than female, and having the lateral parts of last 

 pedigerous segment but slightly expanded and nearly symmetrical. Urosome fully 

 equalling half the length of the anterior division, though, as in the preceding 

 species. composed of only 4 segments. Caudal rami comparatively longer than in 

 female, outermost seta not transformed. Right anterior antennas with the middle 

 section less tumefied than in the type species, and without any dentiform projec- 

 tion of the antepenultimate joint. Chela of right last leg less powerfully developed, 

 thumb simple spiniform, and shorter than the dactylus. 



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



Length of adult female reaching 1.35 mm., of male 1.30 mm. 



Remarks. This form was described by Prof. Lilljeborg in the year 1853 

 as IchtyopJwrba hamata, the generic name referring to the significance of this 

 Calanoid as fish-food, the specific name probably to the peculiar recurved process 

 occurring below the genital segment in the female. The Ichtyophorba angustata 

 of Claus is unquestionably indentical with Lilljeborg's species. It may be easily 

 distinguished from C. typicus by its more slender body, the different form of the 

 lateral parts of the last pedigerous segment and of the genital segment, the soft 

 character of the frontal appendages, the total absence of denticles on the anterior 

 antennae, and, finally, by the less powerfully developed chela of the right last leg 

 in the male. It is, moreover, rather inferior in size. 



Occurrence. The present Calanoid occurs in great abundance in the Chri- 

 st.iania Fjord, even in the immediate neighbourhood of the town, and is also found 

 pretty commonly along the whole southern and western coast of Norway, both in 

 the fjords and in the open sea. North of the Trondhjem Fjord it becomes more 

 ice; but according to the statements of Dr. Aurivillius, it extends as far as 

 the 70th degree of latitude. Like the preceding species, it is a true pelagic 

 form, occurring, as a rule, close to the surface of the sea, and it no doubt forms 



