168 
Transactions of the Royal Society of South Africa. 
the base of the hand-back to the lobe of the movable 
finger. ....... H. gracilis var. nov. nawaquensis. 
(10) Tail very short and stout, about 4| times as long as the 
carapace in the adult male and about 3^-3^ times as long 
as the carapace in the adult female, the first segment 
broader than deep posteriorly in both sexes ; vesicle 
becoming granular inferiorly in the male, quite smooth in 
the female Carapace of female as long as the first two 
caudal segments together ...... II. bicolor Pure. 
(11) Apparently somewhat similar to bicolor, but female Avith 
tail about 4 times as long as the carapace (male unknown). 
Carapace as long as the first caudal segment together 
with ^ of the second H. minor Pure. 
(12) Female with tail 3f times as long as the carapace; first 
segment broader than high; carapace apparently more 
lightly excavated than in Mcolor or minor ; pectinal teeth 
15 (male unknown) H. taeniurus Thor. 
(13) Female with tail 4^ times as long as the carapace; first 
caudal segment higher than broad, the tail segments being 
laterally compressed; anterior margin of carapace only 
lightly excavated; pectinal teeth 14 (male unknown). H. p/ii// lodes Thor. 
C. Anterior margin of carapace deeply excavated; superior crests of 
caudal segments II and III tvith strongly spiniform terminal teeth, 
especially in the adult male, lohere they are often curved forwards ; 
reside quite smooth. 
(14) First caudal segment in the female stout, not or scarcely 
higher than wide posteriorly, but in the male decidedly 
higher than wide ; superior crests of caudal segment V in 
the female weakly denticulated ; pectinal teeth, male 17, 
female 12-14 ....... R. trichiiirtis var. tvhitei. 
(15) First caudal segment of the female not quite so stout as 
in ivhitei ; superior crests of caudal segment V in the 
female not denticulated ; iDectinal teeth, male 19-23, 
female 14-16 trichiunis var. nov. caffer. 
(16) Vesicle and caudal segments more slender than in tvhitei, 
the first segment in the female being decidedly higher 
than broad posteriorly ; superior crests of caudal segment 
V in the female strongly denticulated; pectinal teeth, 
male 16-17, female 13-16 . . . H. trichiurus var, noY. graciloides. 
Gen. OPISTHACANTHUS* Peters. 
O. cAPENSis Thorell (PL XXVIII, fig. 82), Actes Soc. Sci. Nat. Ital. xix, 
p. 246, 1877. 
This species was described as a variety of valiclus from examples collected 
by J. Yictorin at " Caput Bonae Spei." I have little doubt but that the 
* The type of the genus Opistkacanthus is 0. elatus Gervais, a South American 
species. Mr. E. I. Pocock originally separated the African species under a distinct 
