29S Mr. L. A. Borradaile on the 



necessary and that a new genus must be established for one 

 of the new Maldive species. In these circumstances a settle- 

 ment of the question may be forwarded by the following 

 short survey of its position, in the shape of a redefinition of 

 the central group of genera and a key which includes thera 

 with the others of the family. 



The definition of each of the revised genera is followed by 

 a list of those species which I am at present able to assign to 

 it. References to all of these which have been already 

 described will be found in Alcock's work cited in the foot- 

 note. I'he new species will be described in the 'Fauna and 

 Geography of the Maldive Islands,' vol. ii. part 1. 



The features of which I have made use for systematic 

 pu- poses are for the most part those taken by other writers. 

 Tlie principal are : — The presence or absence of an epipodite 

 on the first leg (cheliped), the distinctness or otherwise of 

 tiie furrows on the back which mark off the regions, the 

 proportion of the length of the carapace in tiie middle line 

 to its greatest breadth, the shape of the legs, and the arrange- 

 ment of the sternal furrows. These are a pair of grooves, 

 one on each side, which run fore and aft over the thoracic 

 sternites of the female, beginning on the hindermost and 

 ending on that which corresponds to the first, second, or 

 third pair of legs. Their forward ends may be raised on 

 knobs, and are either wide apait, side by side but not meeting, 

 or curving to meet. 



Definitions of Genera o/Dromildfe. 

 1. Dromia, Fabr. 



" Dromiida? with an epipodite on the cheliped, the walking- 

 legs not knobbed or ridged, the carapace broader than long, 

 the regions well marked or indistinct, the ridges of the 

 efferent branchial channels broken, indistinct, cr well made, 

 the sternal grooves of the female ending apart behind the 

 cheliped segment, the fifth leg shorter than the third and 

 with no thorn on the outer side of its last joint." 



D. vuhjai'is^ D, dormia { = D. Rumphi), &c. 



2. DroMIDIOPSIS, Borradaile. 

 " Dromiidse with an epipodite on the cheliped, the walking- 

 legs not knobbed or ridged, the carapace longer than broad, 

 the furrows between the regions almost completely lost, the 

 ridges of the efferent branchial channels well made, the 

 sternal grooves of the female ending togetlier on the cheliped 

 segment or on that of the first wal' 



