i8 3 



The fifth pairs of feet of the two sexes are quite distinct from the definition given by 

 Sars for the family Parapontellidae, in 'Crustacea of Norway' vol. IV, Calanoida, and it may 

 he found necessary at some future period to establish a new family for the reception oi the 

 members of this genus. 



One species, apparently distinct trom the type. was obtained from the plankton collected 

 by the 'Siboga'. 



i. Baihypontia spinifera nov. sp. Plate III, figs. i — 16. 



Female — length 3,3 mm. 



Seen from above, the body appears considerably elongated, and of nearly cylindrical 

 form. The head is separated from the first thoracic segment. The fourth and fifth thoracic 

 segments are completely segmented. The last thoracic segment is symmetrical. It is produced 

 on each side into wing-like expansions with pointed ends. Seen from the side, the last thoracic 

 segment is broadly triangular in outline. It terminates in small, bluntly rounded, posteriorly 

 directed points. The rostrum is represented by a moderately strong cylindrical filament with 

 a very slight tracé of bifurcation at the apex. 



The abdomen is composed of four segments. The combined length of the abdomen and 

 furca is contained nearly three and one-third times in the total length of the cep halothorax, 

 from the frontal margin to the base of the genital segment. The genital segment is longer 

 than the others. It appears considerably inflated in the region of the genital opening, when 

 viewed from the side. The posterior margin of the first, second and third segments is fringed 

 with fine spines. The furcal joints are very small (Plate III, fig. 3). The illustration shews the 

 segments in a rather telescoped condition. 



The antennules are composed of twenty-three joints and extend to the middle of the 

 fourth thoracic segment. 



The endopodite and exopodite of the antennae are of nearly equal length. The exopodite 

 is composed of seven joints. The intermediate joints are very small and indistinct. 



The mandible and palp are quite distinct from those of Parapontella. The upper end of 

 the biting part of the mandible is armed with two spiniform teeth. The lower end is furnished 

 with a short, stout and densely spinulose seta. The upper half of the intermediate part of the 

 cutting edge is finely serrate. The lower half is fringed with short hairs. The basal part of the 

 palp is short and broad. The exopodite is four-jointed. It is distinctly longer and stouter than 

 the two-jointed endopodite (Plate III, fig. 7). The maxillae are rather more highly developed 

 than in Parapontella (Plate III, fig. 8). 



The first pair of maxillipedes is very strong and resembles slightly that of Parapontella. 

 The spines on the apical portion are long and curved. The distal portion of the spines is slightly 

 flatteneel, and the inner margin is fringed with fine short hairs (Plate III, fig. 9). 



The second pair of maxillipedes is of the ordinary Calanoid type. The basal part is two- 

 jointed. The distal part is composed of five joints (Plate III, fig. 10). 



The exopodites of the four pairs of swimming feet are three-jointed. The endopodite of 



i8.s 



