127 



ii. . 2nd or " subdorsal " crest smooth in its posterior 

 half: anterior half of 4th or "lateral" crest 

 smooth up to its terminal spine: carina? of 2nd 

 and 3rd abdominal terga low and inconspicuous ... G. unguiculata. 



II. The 3rd or " dorso-lateral " crest of the carapace is present, not only 

 behind the cervical groove, but also in front of it as a post-antennal 

 ridge : — 



1. The anterior half of the 3rd or " dorso-lateral " crest runs for- 



ward to and ends in the orbital spine : antennal scale not 



nearly twice as long as broad ... ... ... G. hastacauda. 



2. The anterior half of the 3rd or " dorso-lateral " crest ends in a 



small spine behind and distinct from the orbital spine : 



antennal scale twice as long as broad ... ... G. Gilesii. 



74. Glyphocrangon investigator is, Wood-Mason. 



Glyphocrangon mvestigatoris, Wood-Mason, Ann. Mag. Nat. Hist., Feb. 1891, p. 191 ; and var. andamanensis, 

 id. ib., Nov. 1891, p. 356. 



Illustrations of the Zoology of the Investigator, Crustacea, Plate VI. Figs. 3, 2. 



The rostrum is traversed longitudinally by a very fine median posteriorly- 

 serrated ridge, and is armed on either border with 2 spines, one at the base, the 

 other near the middle ; the length of its free portion is about two-thirds that 

 of the rest of the carapace measured in the middle line ; its base is separated 

 from the gastric region by a groove. 



Except that the anterior half of the 3rd or " dorso-lateral " crest is utterly 

 wanting, all the crests of the carapace are thick and prominent, and the surface 

 between them — like that of the abdominal terga and pleura — is studded with 

 very numerous tubercles which have a tendency to be compressed and to fall 

 into lines parallel with the crests. Amid these tubercles the anterior half of 

 the 2nd, or " subdorsal," crest of the carapace is obscured. 



The orbital and branchiostegal spines are very large and acute, and behind 

 and between them is the huge vertically-compressed wing-like spine in which 

 the lateral crest of the carapace ends, this crest having no other spine in any 

 part of its course. Nor are there any other distinct spines on any of the other 

 crests of the carapace, though the dorsal and subdorsal crests are coarsely 

 serrated in all their extent. The other crests of the carapace, though smooth 

 to the naked eye, have, under the lens, a " worm-eaten " edge. 



The 1st abdominal tergum has three short, anteriorly acute, carina? — one 

 median, and one on either side. 



The 2nd to the 6th abdominal terga have each a median carina, which is 

 divided by a deep notch into two more or less unequal lobes or teeth, and on the 

 5th tergum the posterior half of the carina is trifurcate. 



