BRACHYURA AND MACRURA OF HAWAIIAN ISLANDS. 
841 
Sesarma (Holometopus) trapezium Dana. 
Sesarma trapezium Dana, Crust. U. S. Exploring Expedition, I, 354, 1852; pi. xxii, fig. 8, 1855. 
Hawaiian Islands (Dana). 
Sarmatium faxoni, sp. nov. 
(PI. vii, fig. 1.) 
Carapace very little broader than long. Anterior third inclined. Protogastric and anterior branchial 
regions separately convex. Anterior mesogastric and postorbital regions depressed. H-shaped depres- 
sion* deep. Post-frontal tubercles of the middle pair three times as wide as those of the lateral pair; 
directly behind the latter and a little posterior to the line of the orbits another pair of elevations similar 
but wider. Surface of the anterior two-fifths of the carapace covered with coarse rough granules; the 
remainder with irregular confluent grooves and pits; post-lateral regions obliquely striated. 
Surface of front vertical, not visible or only partially visible in dorsal view, very concave horizon- 
tally and perpendicularly, granulate; margin thin, along the anterior edge very finely crenulate; in 
front view this edge nearly horizontal and slightly sinuous, in subdorsal view 
bilobed; side margins parallel; corners rounded. 
Lateral margins of carapace very convex, marked by a narrow smooth rim; 
three teeth, including the orbital, the first and second directed forward, narrowly 
acute, sharp-pointed, the first the largest; third tooth obtuse, smallest, directed 
outward. 
Arms with a superior subterminal tooth; outer face crossed by short granular 
striae; lower face bordered by spiniform tubercles. Wrist with outer surface very 
rough with striae, and granules; inner tooth broad, blunt. Hands equal in both 
sexes, covered outside and in with large, rather distant, sharp granules. A line 
of smaller granules along upper margin, below which on the inner surface are three 
or four short oblique, granulated ridges. Fingers of male gaping, of female not 
gaping; upper surface of dactylus armed with horny-tipped spinules, one row of 
which extends at least to the distal third of the finger; similar spinules on the lower surface of the pollex. 
Ambulatory legs long and flat, the third pair between 2 and 2j times as long as the carapace. 
The merus joints widen gradually from the proximal end and may attain their greatest width at the 
subterminal spine or somewhat behind that point; subterminal projection a sharp spine. The pro- 
podites are elongate, with subparallel sides. 
Abdomen of mature female very wide; last segment deeply set in the preceding. 
Dimensions. — Male ( Ebon ) , length , measured from edge of post-frontal lobes 41 . 2, greatest width 43, 
exorbital width 30.5, width at posterior epibranchial tooth 38.7, width of front 15 mm. ; female (type), 
length, measured from edge of post-frontal lobes 34.4, greatest width 37, exorbital width 26, width at 
posterior epibranchial tooth 33.5, width of front 13.5 mm. 
Distribution. — Oahu, H. Mann, 1864, one female type (Cat. No. 22837), received from Museum of 
Comparative Zoology, w r here there are additional specimens (3 males, 3 females) from the same locality, 
and three males from Ebon, Marshall Islands, Rev. B. G. Snow, collector. 
Named for Dr. Walter Faxon. 
This species differs from the typical species of the genus, S. crassum Dana, in the vertical front and 
in the terminal segment of the abdomen of the female deeply impacted in the penultimate segment. 
Plagusia depressa tuberculata Lamarck. 
Plagusia depressa var. squamosa Alcoek, Jour. Asiat. Soc. Bengal, LXIX, 1900, 437 (not all 
synonymy). 
Kailua and Hilo, Hawaii; Maui, R. C. McGregor; south coast of Molokai, station 3824; Honolulu; 
Laysan; Hawaiian Islands, W. H. Pease. 
Hawaiian Islands (Stimpson); Laysan (Lenz). 
This form is regarded as a subspecies of P. depressa because there are intergrading forms. Speci- 
mens from Madeira have every appearance of P. depressa from the American coast, except that the 
lobe on the basal joints of the legs is entire, as in true tuberculata. P. immaculata seems to me a 
distinct species. The designation squamosa Herbst is not used ior' tuberculata Lamarck in view of the 
fact that there appears to be doubt as to the identity of the type of the former. 
Fig. 5. — Sarmatium 
faxoni , abdomen 
of male cotype, 
Xf. 
