162 
Transactions of the Royal Society of South Africa. 
anterior margin of the carapace is lightly excavated in gracilis but straight 
in troglodytes, the latter has no spiniform terminal teeth on the superior 
crests of caudal segments II and III, and the last tergite of the male is 
relatively broader than in gracilis. Nevertheless I am inclined to suspect 
that the two forms will prove to be linked up by intermediates. The last 
tergite of the male is sometimes quite as long as broad, at other times 
rather broader than long ; the terminal tooth of the superior crest of caudal 
segment III may be spiniform or only subspiniform ; the anterior margin 
of the carapace may be moderately excavated or only very slightly so. 
The superior caudal crests in the male are not definitely denticulated 
or only weakly so. The fourth caudal segment of the male is devoid of an 
enlarged, almost subspiniform, terminal tooth, as often occurs in gunningi ; 
the vesicle is not deep as in that species, and the last tergite is relatively 
longer in gracilis than in gunningi. The shape of the vesicle affords a ready 
means of distinguishing between females of gracilis and gunningi ; in 
gracilis the vesicle is decidedly more elongated in proportion to its depth. 
In adult female specimens of gracilis and gunningi the measurements of the 
vesicle are respectively, height 3, 3, length 8'5, 6' 75. 
The Albany Museum possesses a distinct form of this species from 
O'okiep (Dr. E. Howard). This I now describe under the name of 
H. gracilis var. namaquerisis (PI. XXXII, fig. 92). The adult male from 
O'okiep very closely resembles that of typical gracilis, but differs as follows ; 
Fifth caudal segment slightly longer ; vesicle smooth on the sides, except 
inferiorly, whereas in gracilis it is finely granulated almost throughout ; the 
granules composing the supero-anterior crest of the humerus are more 
numerous (18-20) but smaller than in typical gracilis (13-14); upper 
surface of humerus narrower than in gracilis and almost quite flat, not 
shallowly excavated as in typical gracilis. The measurements are as follows : 
Total length 165 ; length of carapace 13-4, width of same 13 ; width of hand 
7*1, length of hand-back 14*5, of movable finger 13-3 ; length of last sternite 
10'5, breadth of same 10 ; first caudal segment 16*25 long, 3-25 high, 2*6 
broad posteriorly ; second caudal segment 20*4 long, third caudal segment 
20*4 long, fourth caudal segment 23 long, fifth caudal segment 20-6 long ; 
vesicle 8*25 long, 2*6 high. Superior crests of caudal segments II and III 
weakly but numerously toothed throughout except immediately in front, the 
terminal tooth only a little enlarged. Pectinal teeth 18. 
The female is unknown to me. 
This form is presumably the same as that taken at Steinkopf and 
Kamaggas by L. Schultze, and referred to by Kraepelin (11) as taeniurus 
Thorell ; subsecjuently, that authority seems to regard it as distinct from 
Thorell's species (12). I think it cannot possibly be taeniurus in view of 
the stoutness of the first caudal segment in that species. 
