I.SOMEIEUS. 51 



basal portion, and base of digits infuscate ; legs externally varie- 

 gated. Upper side of body closely aud entirely covered with 

 larger and smaller granules ; a row of coarser granules along 

 posterior border of terga ; last stern urn closely granular throughout, 

 and furnished with four granular keeK Tail slender, about four 

 times as long as carapace, closely granular, normally keeled ; 

 median lateral keel present only on 1st segment, merely represented 

 on the 2nd posteriorly by about three granules ; vesicle smooth, 

 long, about twice as long as aculeus ; spine large, triangularly 

 pointed, its inferior edge continuous with the corresponding edge 

 of the vesicle, its upper edge furnished with a pair of tubercles ; 

 distance between spine and base of aculeus scarcely equal to diameter 

 of base of aculeus; aculeus moderately long. Chelce with humerus 

 and brachium granular and normally keeled ; brachium wide, only 

 twice as long as wide, and furnished in front with about half-a- 

 dozen denticles; hand large, wider than brachium, smooth, not 

 crested ; fingers short, in contact, movable only slightly longer 

 than underhand, furnished with 7 rows of teeth. Pectinal teeth 

 12-13. Tarsi furnished below with a few setae, arranged in two 

 rows. 



Measurements in mm. Total length 23, tail 13, carapace 3. 



Loc. Madras (Henderson). 



A single female example. 



'39. Isometrus acanthums, Pocock, Jour. Bom. JY. H. Soc. xii, p. ^64, 

 1899. 



d . Allied to the preceding species, and most nearly resembling 

 J. basilicus in colour. Carapace lined with black ; anteocular 

 region black, with a few small yellow spots ; terga with six yellow 

 and five black longitudinal bands ; 4th and oth sternal plates lined 

 with black ; tail delicately lined with black ; chelae and legs yellow 

 spotted with black, black on brachium predominating and circum- 

 scribing definite yellow spots ; hand almost entirely yellow, not 

 black at base of fingers ; fingers not black, but yellow and spotted 

 with black. Upper side of trunk granular, and crested as in 

 the preceding species ; carapace as long as the 2nd caudal segment ; 

 5th abdominal sternum marked with four complete and equal 

 granular keels. Tail long and slender, about seven times the 

 length of the carapace ; keels stronger than in /. basilicus, and the 

 terminal granule on the superior keels on 2nd and 3rd segments 

 long, erect, and spiuiform; vesicle with coarsely granular crests 

 below ; spine not so thick as in the preceding species, triangular, 

 but with blunt, not rounded or sharp apex, armed with only two 

 denticles ; aculeus short and curved. Chelcn much as in /. basilicus, 

 but the front of the brachium normally crested and subdenticulate, 

 not furnished with a few large teeth ; hand smooth, wider than 

 brachium, its width about half the length of the underhand; movable 

 digit as long as underhand, not so long as carapace, furnished with 

 7 rows of teeth. Pfctinal teeth 10. 



E2 



