AETHEOPOD FAUNA OP THE WEST INDIES. 375 



c'. The individual rows of the median 

 series of teeth on the digits scarcely 



overlapping Isometrus. 



6*. The individual rows of the median 

 series of teeth overlapping for half 



their distance Tityus. 



b^. The intervals between the teeth of the 



lateral series occupied by longitudinal 



series of denticles. 



a^. Pectines only moderately dilated at 



the base ; the first abdominal sternite 



not sulcate Centrurus, 



P. Pectines strongly dilated at the 

 base ; the first abdominal sternite 



bisulcate Heteroctenus, nov.r 



b. Sternum pentagonal or transversely elon- 

 gate owing to antero-postei'ior compres- 

 sion, 

 a*. Sternum pentagonal, distinct and large, 

 a^. With a distinct and large tubercle 

 beneath the aculeus. 

 a^. With three lateral eyes on each 



side DiPLOCENTRUS, 



¥. With two lateral eyes on each 



side OiCLUS. 



b^. Without a tubercle beneath the acu- 

 leus. 

 a'. Tail strongly compressed ; the 

 anterior border of the carapace 

 strongly excised in the middle ; 

 three lateral eyes ; sternum as 



wide as long Opisthacanthus. 



6''. Tail not compressed ; the anterior 

 border of the carapace entire ; 

 two lateral e5'es on each side ; 



sternum wider than long Broteochactas.^ 



6*. Sternum transversely elongate, strongly 



compressed antero-posteriorly. 



a^. With a large tooth on the lower 



border of the movable digit of the 



mandibles; upper surface of the 



tarsi not carinate Hadrurus.] 



b^. Lower edge of the movable digit 

 of the mandible unarmed ; upper 

 edge of the tarsi carinate Brachistosternus, novo 



