CRITSTACEA OF NORTHUMBERLAND AND DURHAM 36 1 



This species, hitherto referred by most authors to Monoailus 

 finmarchian Gunner, is considered by Professor G. O. Sars to 

 be distinct. Gunner's description referring to a closely allied 

 form which is chiefly Arctic in its distribution, and differs in 

 its greater size and in some not very important structural 

 details.* So far as we at present know the true C. finmarchicus 

 does not occur in our district. C. sepfentrionalis, on the 

 contrary, is often found in immense numbers, usually near 

 the surface in the open sea, but often also in pools of the 

 littoral zone where it has doubtless been left behind by the 

 retreating tide. N.D. 



Fam. 2.— PSEUDOCALANID.^ 



PSEUDOCALANUS ELONGATUS Boeck. 



1865. Calanus Clausii, Brady, Nat. Hist. Trans. Northum- 

 berland and Durham, vol. i., p. 33, pi. i., figs, i, 

 11-13. 



1878. Pseudocalanus elongatus, Brady (3), vol. i., p. 45 

 pi. iii., figs. 1-9. 



Very common both in the open sea and in tidal pools. N.D. 



Fam. 3.— CENTROPAGID.*: 

 Centropages typicus Kroyer. 



1863. Ichthyophorba denticornis, Glaus (2), p. 199, pi. xxxv., 



figs. I, 3-9. 

 1865. Ichthyophorba denticornis, Brady, Nat. Hist. Trans. 



Northumberland and Durham, vol. i., p.. 40, pi. iv., 



figs. 1-6. 

 1878. Centropages typicus, Brady (3), vol. i., p. 65, pi. viii., 



figs. i-io. 

 1901. Centropages typicus, G. O. Sars (6), vol. iv., p. 75, 



pis. xlix., 1., li. N.D. 



• The Britisli form was, howeTer, described by H. Goodsir in 1843 under the 

 specific name septentrionalis, and as pointed out in the " Crustacea of Devon and 

 Cornwall," that name must be adopted if the still earlier one used by Gunner be 

 held to apply to a rtitfereut species. 



