32 THE BRACHYURA. 
J 
The genus Ptychognathus already comprises 12 species and 1 subspecies, 
all Indo-Pacific. Our species is most closely related to P. polleni de Man,* 
from Madagascar, in which the carapace is narrower and front wider, and 
the branchial ridge arises near the last lateral tooth. 
Pseudograpsus albus Stimpson. 
Pseudograpsus albus Kingsley, Proc. Acad. Nat. Sci. Phil., 1880, 205. 
Fakarava Island, Paumotus; outer reef; Oct. 12, 1899; 1 ? juv. 
Hemigrapsus elongatus (A. Milne Edwards). 
Pl. 2, Fig. 2; Pl. 7, Figs. 2, 2a. . 
Heterograpsus elongatus A. Milne Edwards, Nouy. Arch. Mus. Hist. Nat. Paris, 1873, 
9, 317, pl. 17, fig. 5. 
Tongabatu, shore ; Nov. 22, 1899; 1 ¢. | 
The fronto-orbital width is a little less than the length, while the greatest — 
width of the carapace exceeds the length. Carapace almost smooth and — 
punctate, the punctae unequal in size and distribution. Posterior angles — 
of mesogastric region deeply marked. The postero-external surface of 
the branchial region is very steep, and its upper margin is stronger 
than the lower, and continued nearly to the posterior margin of the | 
carapace. Front very nearly half as wide as the carapace; the lobes of 
margin are separated by a broader sinus than shown in Milne Edwards's — 
figure. Upper margin of orbit sinuous, a notch at the inner end. Lateral 
teeth blunt, formed by small triangular notches, the distance between them 
less than the distance from the first to the orbital angle. 
The left cheliped only is present. Merus and carpus unarmed, the 
inner angle of the latter bluntly rounded. Palm nearly as high as long, 
and longer than the fingers, measured horizontally. The longitudinal 
ridge on the lower half of the palm occupies only the proximal half. 
Fingers strongly gaping. The large patch of thick hair on the inner 
side of the chela extends half way on the palm and half way along the 
pollex, and partly along the occludent edges of the fingers, even to the 
outer side of the articulation of the dactylus. 
The ambulatory legs are chiefly light colored, with a few narrow bands 
of the dark color of carapace and cheliped. They are sparsely furnished 
with fine hairs. 
1 Op. cit., 1895, 9, 94; 1898, 10, pl. 28, fig. 20. 
