137 



species has also been taken by Mr. Nordgaard in the neighbourhood of Bergen; 

 and 2 specimens were further found in a plankton-sample taken during the cruise 

 of the "Michael Sars" in 1901, at Stat. 11, located east of Iceland. 



Dixtriliittiwi. British Isles (Brady), Atlantic Ocean, between Lat. 33 

 and 50 N. (Cleve), Mediterranean (Giesbrecht). 



Fam. 21. Pontellidae. 



Characters. Body generally strongly built, with the anterior division more 

 or less fusiform in shape. Cephalosome well defined from the 1st pedigerous 

 segment, and having often laterally a hook-like projection, front produced below 

 to a strong bifurcate rostrum. Last segment of metasome with the lateral parts, 

 as a rule, produced behind. Urosome in female generally asymmetrical, with the 

 number of segments more or less reduced. Caudal setae present in the normal 

 number. Visua} organs, as a rule, highly developed, consisting of a single pro- 

 tuberant ventral eye and 2 well defined dorsal eyes, each often provided with 

 one or 2 cuticular lenses. Anterior antennae in female 16 24-articulate ; right 

 antenna in male distinctly geniculate, with the middle section generally greatly 

 tumefied. Posterior antennae resembling in structure those in the Candaciidce. 

 Mandibles and maxillae on the whole normal. Anterior maxillipeds strongly built, 

 with long, anteriorly-curving spiniform setae, digitiform lobes well developed. 

 Posterior maxillipeds much smaller than the anterior, with the 1st basal joint 

 more or less expanded and carrying long setae, remaining part very narrow, and 

 clothed with very short setae. The 4 anterior pairs of legs of normal structure, 

 with the inner ramus shorter than the outer and generally biarticulate. Last 

 pair of legs not natatory in either of the sexes, though in female generally 

 biramous; those in male very asymmetrical, right leg more or less pronouncedly 

 cheliform. No ovisac present in female. 



Remarks. This family, answering to the 'subfamily Pontellina of Gies- 

 brecht, comprises a number of Calanoids, which are distinguished by their strongly 

 built body and the often vivid blue colour with which they are ornamented. Of 

 all the known Calanoida, they seem to be those which have reached to the highest 

 degree of development, this being manifested both by their unusually energetic 

 movements and the generally complicated structure of the visual organs. In the 



19 Crustacea. 



