Boone, Crustacea, Cruises of ''Eagle" and ''Ara," 1921-28 207 



Family: IDOTHEIDAE. 



Genus: IDOTHEA Fabricius. 



Idothea metallica Bosc. 



Plate 78. 



Diagnostic characters : Body oblong-ovate ; telsonic segment trun- 

 cate at its extremity. 



Type: Described as *'an inhabitant of the sea." 



Distribution : Pelagic and bathypelagic in the North Atlantic, off 

 both American and European coasts ; also in the Mediterranean Sea ; 

 depths ranging from surface on floating weed to 91 fms. The "Ara" 

 specimen was taken when the dredge was 900 fms. down. 



Material examined: Two specimens taken S. by E. of Monaco, 

 Mediterranean Sea, 900 fms., April 19, 1927, by the "Ara," William 

 K. Vanderbilt, commanding. 



Color: Iridescent blackish-grey, or slaty-steel color. 



Technical description: Body oblong-ovate, the greatest width 

 across the third thoracic segment, decidedly convex from side to side, 

 narrowing posteriorly. 



Head: Subrectangular, 1.5 mm. long, 3 mm. wide; anterior mar- 

 gin slightly excavate, anterolateral angles deflected, rounded, a\ 

 slightly curved, transverse groove across the head not far from the 

 posterior margin; posterior margin slightly excavate. The eyes are 

 large, compound, convex, situated at the anterolateral angles, shining 

 black. 



Thorax : The first thoracic segment is about as long as the anterior 

 portion of the head and has its lateral parts expanded, the antero- 

 lateral angle rounded and fitting close to the head ; the second, third 

 and fourth segments are subequal in length to the first segment and 

 to each other; the fifth, sixth and seventh segments are subequal to 

 each other, each about three-fifths as long as the fourth segment ; the 

 second to seventh segments, inclusive, have the epimeral plates articu- 

 lated ; the first and second epimera with the postlateral angle rounded ; 

 the remaining epimera with this angle right-angled, or obtuse. 



Abdomen : This consists of three distinctly separated and one partly 

 fused segment. The first and second segments are slightly shorter 

 than the last thoracic segment and have their lateral angles acute ; the 

 third segment is fused in the medina region with the telson, separated 

 laterally, about as long as the preceding segment. The telson is 4.1 



