223 



lished by MM. Giard and Bonnier as Dajus mixtus, but this is only a nominal 

 species, and undoubtedly identical with tbat originally recorded by Kr0yer. 



Dajus mysidis, Kreyer. 



(PL XCIII, CIV). 



Dajus mysidis, Krayer, in Gaimard's Voyage, PI. XXVIII, fig. 1. 



Syn.: Bopyrus mysidum, Packard 



„ Leptophryxus mysidis, Buchholz 



„ Dajus mixtus, Giard and Bonnier. 



Specific Characters. — Body of fully grown female oval quadrangular in 

 outline, broadest in front and slightly narrowed behind. Cephalon imperfectly 

 defined, and curved downwards, frontal margin straight. Lateral parts of meso- 

 some greatly swollen, and projecting anteriorly in the form of bluntly rounded 

 protuberances extending beyond the limits of the cephalon, median part sub- 

 depressed and exhibiting 5 or 6 distinct transversal sutures defining the seg- 

 ments. Metasome rather short and but slightly projecting, being conically 

 tapered, its 1st segment much larger than the others. Oral area placed wholly 

 in front, comparatively broad, semicircular. Antennulae very short, 3-articulate ; 

 antennae much more slender and extended laterally, being composed of 8 or 9 

 articulations successively diminishing in size distally. First pair of incubatory 

 plates larger than the next succeeding ones, and divided by a transversal fold 

 into 2 segments ; last pair, extending behind the oral area, rather broadly over- 

 lapping each other in the middle. — Body of young female narrower, subclavate. 

 with the mesosome more distinctly segmented, and the metasome more produced; 

 that of still younger female oblong, attenuated behind, with the cephalon freely 

 projecting in front, and the coxal plates occupying the side-edges of the meso- 

 some.— Body of immature female, immediately after the metamorphosis, still nar- 

 rower, somewhat resembling the male in shape, but having only 5 pairs of legs, 

 and the metasome distinctly segmented. — Adult male linear, subcompressed, with 

 the 6 posterior segments of mesosome very sharply marked off from each other, 

 metasome forming a thickish, undivided piece of oval or elliptical form, carrying 

 at the tip 2 extremely small appendages (rudiments of uropoda). Colour of 

 female along the middle of the dorsal face reddish brown, lateral parts whitish. 

 Length of fully grown female 4 mm., that of male 1 mm. 



Remarks. — As above stated, this form was first recorded by Kroyer, and 

 figured by him in Gaimard's work from a not yet fully developed specimen. The 

 same form was subsequently described under two different names, viz., by Packard 



