ISOPODS OF NORTH AMERICA. 573 



98. Genus DAJUS Kr0yer. 



Female with the head distinct. Middle part of dorsal surface of 

 thorax distinctly segmented. 



Abdomen abruptly narrower than the thorax; all six segments 

 distinct. 



Uropoda present in the form of two simple lamellae, close together. 



Five pairs of incubatory plates present. 



Five pairs of legs present, short and thick, and of similar structure. 



First pair of pleopods well developed, consisting of a pair of simple 

 large lamellae, placed behind the last pair of incubatory plates; follow- 

 ing pairs of pleopoda rudimentary. 



Male with the segments of the abdomen not distinct. Pleopoda 

 wanting. Uropoda rudimentary, in the form of two small, almost 

 inconspicuous lobes. 



DAJUS MYSIDIS Krtfyer. 



Dajus mysidis KR0YER, Voy. en Scand. Crust., 1849, pi. xxvin, fig. 1. 



Bopyrus mysidium PACKARD, Mem. Bost. Soc. Nat. Hist., I, 1867, p. 295, pi. vni, 

 fig. 3. 



Leptophryxus mysidis BUCHHOLZ, Zweite Beutschie Nordpolfahrt, 1874, p. 288, pi. 

 ii, fig. 2. 



Dajus mysidis LUTKEN, Crustacea of Greenland, 1875, p. 150. G. O. SARS, Arch. 

 Math. Nat., II, 1877, p. 354 (254). SMITH in HARGER, Proc. U. S. Nat. Mus., 

 II, 1879, p. 158. HARGER, Report U. S. Comm. of Fish and Fisheries, 1880, 

 Pt. 6, p. 312. HAXSEN, Videnskabelige Meddelelser fra den Naturhistoriske 

 Forening i Kj0benhavn, 1887-88, pp. 197-198. SARS, Crust, of Norway, II, 

 1899, pp. 223-224, pis. xcm, xciv. AXEL OHLIN, Bihang till k. Sv. Vet.- 

 Akad. Handl., XXVI, Afd. iv, No. 12, 1901, p. 39. RICHARDSON, Proc. 

 U. S: Nat. Mus., XXIII, 1901, p. 579. 



Localities. Labrador; Greenland; Kingigtok; Duck Island; Murch- 

 ison Sound; Claushavn; latitude 73 48' north, longitude 80 30' 

 west; latitude 72 33' north, longitude 71 30' west; latitude 71 57' 

 north, longitude 73 56' west; latitude 66 33' north, longitude 61 50' 

 west; latitude 64 56' north, longitude 66 18' west; west coast of 

 Norway; Kara Sea; Sabine Island; Spitzberg; Jan Mayen; Murman 

 coast. 



Depth. Three to 20 fathoms. 



Parasitic on Mysis oculata (O. Fabricius). 



" Body of fully grown female oval quadrangular in outline, broadest 

 in front and slightly narrowed behind. Cephalon imperfectly defined 

 and curved downward, frontal margin straight. Lateral parts of 

 mesosome greatly swollen and projecting anteriorly in the form of 

 bluntly rounded protuberances extending beyond the limits of the 

 cephalon, median part subdepressed and exhibiting 5 or 6 distinct 



See Sars for characters of genus, Crust, of Norway, II, 1899, p. 222. 



