122 



Vs of the length of the anterior division, genital segment somewhat dilated in 

 its anterior part, and about the length of the 3 succeeding segments combined. 

 Caudal rami of moderate size and slightly divergent, setae not very different in 

 length, and densely plumose, the outermost one issuing from a separate ledge of 

 the outer edge, the others from the transversely truncated tip. Anterior antennae 

 of quite extraordinary length, being more than twice as long as the whole 

 body, and very slender, with some of the bristles greatly elongated and extending 

 in different directions. Posterior antennse with the inner ramus greatly produced 

 and very slender, outer ramus scarcely more than l / a as long, and composed of 

 7' articulations. Legs of 2nd to 4th pairs with the inner ramus scarcely half as 

 long as the outer, terminal joint of the latter about as long as the other 2 com- 

 bined, and somewhat narrowed distally. Last pair of legs with a slender seta 

 issuing from the outer corner of the 2nd basal joint. 



Colour. Body highly pellucid, and almost perfectly hyaline. Length of 

 adult female 2.15 mm. 



Remarks. This form, first described by Glaus from the Mediterranean, 

 is easily recognizable from the other species of this genus by the excessively 

 elongated anterior antenna, and by the slight, knob-like projection of the front. 

 It is also rather inferior in size to most of the other species. 



Occurrence. A solitary, but well-preserved female specimen of this form 

 was found in a plankton-sample taken during the cruise of the "Michael Sars" 

 in 1901, at Stat. 25 a, located between Finmark and Bear Island. 



Distribution. Mediterranean (Glaus), Atlantic and Pacific Oceans between 

 26 N. and 40 S. Lat. (Giesbrecht), gulf of Guinea (Scott). 



53. Haloptilus acutifrons, Giesbr. 



(PL LXXXIH, fig. 2). 



Hemicalanus acutifrons, Giesbrecht, Pelagische Copepoden. Fauna d. golf. Neapel, p. 384, PI. 3, 

 fig. 11, PL 27, fig. 12, PL 42, figs. 12, 20. 

 Syn: Hemicalanus spinifrons, G. O. Sars. 



Specific Characters. Female. Anterior division of body, seen dorsally, 

 narrow oblong in form, greatest width only slightly exceeding J /4 of the length, 

 and occurring somewhat in front of the middle, anterior extremity produced to a 

 long spiniform projection pointing straight anteriorly, posterior gradually narrowed. 

 Cephalosome occupying more than half the length of the body, rostral prominence 

 very slight and somewhat remote from the frontal edge, tentacular filaments rather 

 slender. Urosome very short and somewhat thicker than in H. longicornis, other- 



