73 



habitus does not exhibit such great sexual dissimilarity as is often met with in the 

 Amphascandria. The males, moreoTer, occur in about the same number as the 

 females, whereas in the above-mentioned section, male specimens are, as a rule, 

 very rare, and apparently confined to certain seasons. 



The subdivision of this section is connected with no small difficulty, 

 owing to the great variation in the structure of the several appendages. In his 

 great work, Dr. Giesbrecht only records 3 families belonging to this section, viz., 

 the CentfopagidcB, the Oandaeida and the Pontellidce, the first being subdivided 

 into 4, and the last into 2 subfamilies. According to the plan followed in the 

 present account, these subfamilies are here raised to the rank of true families, 

 and their number has moreover been considerably increased. I think we must at any 

 rate admit the following 14 families: Centropagidce, Diaptomidoe, Pseudodiaptomidce, 

 Lucicutiidas, Temoridas, Metridiidce, Heterorhabdidoe, Arietellidce, Candaciidce, 

 Pontellidce, Parapontellidoe, Acartiidce, Tortanidce, Pseudocyclopidoe. With the 

 exception of the Pseudodiaptomidce 1 ), the Lucicutiidce 2 ) and the Tortanidce *), all 

 these families are represented in the fauna of Norway, and they will be mentioned 

 in the following pages, short diagnoses being given of each of them. 



Fam. 13. Centropagidae. 



Characters. Cephalosome well defined from the 1st pedigerous segment, 

 front with 2, generally soft appendages below. Last 2 segments of metasome 

 likewise, as a rule, well defined. Urosome consisting in female of 3, in male of 

 4 or 5 segments; caudal rami more or less elongated, with the full number of 

 setae. Anterior antennae consisting in female of 24 or 25 articulations; right 

 antenna in male distinctly geniculate. Posterior antennae and oral parts on the 

 whole normal. The 4 anterior pairs of legs with both rami 3-articulate. Last 

 pair of legs in female biramous, natatory, outer ramus with a strong unguiform 



!) In this family, I propose to include the 2 genera Pseudodiaptomus, Herrick, and Poppetta, 

 Kichard, which are undoubtedly nearly related, and together form a natural group somewhat 

 intermediate between the Diaptomidae and the Temoridw. 



2 ) This family, answering to the sub-family Leuckartiince of Giesbrecht, contains the following 

 3 genera: Lucicutia, Giesbr., Isochwta, Giesbr., and Disseta, Giesbr. 



3 ) This family is established to include the 2 anomalous genera, Tortanus, Giesbr. ( Corynura 

 Brady) and Mormonilla, Giesbr. 



11 Crustacea. 



