COPEPODS OF THE WOODS HOLE REGION 427 



ke:y to the species (females) 



1. Body more than twice as long as wide ; carapace smaller than 



genital segment ; plates of fourth segment with circular dots 



coleoptratus (p. 427) 



Body less than t\\nce as long as wide; carapace as large as 

 genital segment ; plates of fourth segment without dots 2 



2. Dorsal plates of fourth segment with denticulate margins and 



spines at their anterior corners denticulatus (p. 428) 



Dorsal plates of fourth segment with smooth margins and with- 

 out spines at their anterior corners torpedinis (p. 429) 



ECHTHROGALEUS COLEOPTRATUS (Guerin) 



Plate 27 



Dinematura coleoptrata Gxj^rin, Regne animal de Cuvier, pi. 35, fig. 6, 1837. 

 Echthrogaleus coleoptratus Wilson, Proc. U. S. Nat. Mus., vol. 33, p. 367, pi. 19, 

 1907. 



Occm^^ence. — Found on the skin and fins of the sharp-nosed mack- 

 erel shark {Isvjrus tigris) and the brown shark {C archarhinus mil- 

 herti) at Woods Hole. 



Distribution. — Indian Ocean (Johnston, Milne Edwards) ; English 

 seas (Baird, White, Stebbing, Scott) ; North Atlantic (Steenstrup 

 and Liitken) ; Bohuslan (Olsson) ; Faroe Islands (Hansen) ; coast of 

 Italy (Brian) ; South Africa (Stebbing) ; Woods Hole (Smith, 

 Rathbun, Wilson). 



Color. — Body a dull grayish yellow, lighter on the ventral, darker 

 on the dorsal surface ; the center of the carapace and the entire dorsal 

 plates of the fourth segment chestnut-brown ; eye brownish red. 



Female. — Body more than twice as long as wide ; carapace orbicu- 

 lar, as wide as long, much shorter and a little narrower than the 

 genital segment; dorsal plates of the second segment widely sepa- 

 rated, lateral and oblique; those of the third segment median, fused 

 across the midline, and scarcely reaching the posterior margin of 

 the segment; those of the fourth segment trapezoidal, reaching the 

 center of the genital segment and showing a pattern of transparent 

 circular dots. Genital segment elliptical, longer than wide, with a 

 deep posterior sinus; rudiments of fifth legs on under surface of 

 posterior lobes and invisible in dorsal view. Abdomen wider than 

 long, invisible dorsally, or partly visible ; caudal rami laminate, each 

 with six spines. Total length, 12-14 mm. 



Male. — Carapace suborbicular, a little wider than long, with 

 smoothly rounded margins; frontal plates of moderate width and 

 strongly arched; posterior lobes narrow and curved inward at their 

 tips like those of the female ; accessory lobes small, separated from the 

 lateral lobes by the width of the transparent margin of the latter ; eyes 

 almost invisible. Second segment with lateral lobes extending diago- 



