BKACHYURA. 429 



podites of walking legs which are nearly white), eye stalks dark purplish-red (as 

 dorsum of carapace), lens black." 



The exopodite of external maxilliped bears a slender flagellum a point which is to 

 be noted, for ALCOGK>uses the absence of a flagellum as a generic character, speaking 

 of it in his key as present in Grapsus and absent in Geograpsus. The two genera 

 are, however, distinguished at once by the very striking fringe of hair on the apposed 

 borders of the coxae of walking legs 2 and 3 present in Geograpsus, absent in 

 Grapsus. 



Metopograpsus messor (FORSKAL, 1775) A.G, p. 397. 



Locality : Trincomalee, four specimens. 

 Description: C.I. of an o vigorous female = 16 '00. 



Sesarma edwardsi, var. brevipes, DE MAN, 1889 (' Zool. Jahrb. Syst.,' iv., p. 425). 



Locality : Mouth of a stream near Galle, one specimen. 

 Description: An adult male, C.l. = 9*50. 



Leiolophus planissimus (HERBST, 1804) A.G, p. 439. 

 Locality : Galle, lagoon, two specimens (small, immature). 



Plagusia depressa (FABR.), var. immaculata, LAMK., 1818. 



Localities : Cheval Paar, four specimens (a, b, c, d) ; Navakaddu Paar, one 

 specimen (e). 



Description: C.I. C.b.H-C.l. Post.bord.C.-=-C.l. Fronto-orb.b.-rC.l. 



(a)ovigerous ? . . 29'00 1'09 0'59 0'66 



(b) ovigerous ? . . 24'25 1'08 0'58 070 



All come definitely under P. immaculata of MIERS' revision (' Ann. Mag. Nat. 

 Hist.,' (5), i., p. 150, 1878). The tubercles are naked in all. 



Remarks. There is some confusion of terminology in regard to this and allied 

 forms. ALCOOK writes " Plagusia depressa) var. squamosa (HERBST)," which is 

 interpreted by BORRADAILE as " Plagusia depressa (HERBST), 1783 [misprinted as 

 1793], var. squamosa, HERBST, 1790." This can hardly be ALCOCK'S meaning, for 

 then (l) squamosa would = depressa and (2) FABRICIUS had already used depressa in 

 a different sense. I take ALCOCK to mean " Plagusia depressa (FABR.), 1775, var. 

 squamosa, HERBST, 1790," which implies two things: (1) a development of MIERS' 

 views in bringing together under one species the three (P. depressa (FABR.), 1775, 

 P. tuberculata, LAMARCK, 1818, and P. immaculata, LAMARCK, 1818) recognised by 

 the latter in his excellent revision of the Plagusiidse ; (2) a union of the P. tuberculata 

 and P. immaculata as a single variety within the species so formed. I agree with 

 the first suggestion, but cannot accept the second. 



Plagusia depressa (FABRICIUS), 1775, may be divided as follows: 



