68 University of California Publications. [Zoology 



Genus Xanthocalanus Giesbrecht. 



XanthocaJanus, Giesbrecht ('92), p. 57, 286; ('98), p. 49. 



Head separate from thorax, fourth thoracic segment fused 

 with fifth. Abdomen of female 4-segmented, symmetrical. An- 

 terior antennae reaching to end of body at least, 24-jointed. Ab- 

 domen of male 5-segmented; right anterior antenna 17-joiuted. 

 Anterior maxilliped provided with characteristic sensory append- 

 ages, some of them pencillate (PI. 12, fig. 60). The mandible, 

 maxilla, and first maxilliped reduced in the male, the latter with 

 but one pencillate sensory appendage. Swimming feet of both 

 sexes as in Scolecithrix; fifth feet in female 2-, 3-, or 4-jointed. 

 The right fifth foot is lacking or .shortened in the male, the left 

 uniramous 5-jointed. 



Xanthocalanus similis n. sj) 



PI. 9, fig. 1; pi. 10, fig. 24; pi. 12, figs. 60, 61; pi. 13, figs. 71, 77. 



Female : Head with a crest, rostrum short and heaw, bifid ; 

 the last thoracic segment ends laterally in sharp angles, but not 

 spines (PI. 9, fig. 1). Genital and anal segments equal in length, 

 the second segment the longest of the four. Anterior antennae 

 extend back as far as the posterior border of the cephalothorax. 

 The anterior maxilliped has seven pencillate sensory appendages 

 and one long, vermiform process (PI. 12, fig. 60), and a very long, 

 heavy, curved hook on the terminal lobe. The second maxilliped 

 has a short pencillate sensory process on the outer margin of the 

 first basal near the base of the joint. Swimming feet as in other 

 species of the genus, except that the terminal saw in the second, 

 third (PI. 13, fig. 71), and fourth pairs has a second row of teeth 

 inside the usual denticulations. The second row, extending from 

 the base of the saw, is about one-third the length of the latter. 

 The fifth feet are clearly 4-jointed (PI. 13, fig. 77) and thickly 

 covered with spines ; the last joint ends in two short, heavier 

 spines, the terminal one longer than the outer one. There is a 

 somewhat similar terminal spine on the outer margin of the third 

 joint of the foot. 



