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210": CRABS OF THE FAMILY PERICERIDA—RATHBUN. 
variations from those described by A. Milne Edwards, and some of them 
are identical with Kingsley’s Mithraculus hirsutipes. The specimens 
intermediate in size present every gradation in character between the 
large and small and prove the two extremes to be variations of one 
species. 
Carapace subtriangular, comparatively smooth, the large specimens 
with scattered punctures, the small ones deeply sculptured. In large 
specimens three grooves run diagonally backward from near the first, 
second, and fourth sinuses of the antero-lateral margin to the cardiac 
region. There are six or seven depressed tubercles along the margin 
and on the posterior part of the branchial region, two or three along 
the outer margin of the hepatic region, and two pairs on the frontal 
region directly behind the lobes of the rostrum. In small specimens 
the grooves are deeper and the tubercles more prominent; the outline 
of the mesogastric region is well defined; and there are depressed 
tubercles on the anterior part of the gastric region. 
Lobes of rostrum short, broad; median notch broadly V-shaped. 
Orbital angles acute, internal angle prominent. 
Antero-lateral teeth four, acute, slender, separated by broad rounded 
sinuses, the first the shortest and in large specimens subacute, the 
remainder sharp and directed forward, the second one usually the 
longest and largest. In some specimens there is a small tifth tooth on 
the postero-lateral margin just back of the fourth tooth. 
In large specimens, chelipeds proportionately larger, strong and 
smooth. Merus with five spines or spiniform tubercles on the upper 
margin, two on the inner face just below the margin. On the inner 
margin are two prominent teeth, the anterior one often more or less 
flattened, broad and obtuse, the posterior one sometimes with a lobe on 
its posterior margin. Carpus rounded, smooth, sometimes unarmed, 
often with a short spine or tubercle on the inner margin, anterior to 
the inner angle, which is often produced in a less conspicuous promi- 
nence, giving the carpus the appearance of being double-toothed. 
Hands from the articulation to the tips of the fingers much longer 
than the carapace, broad, compressed; upper and lower margins nearly 
parallel. Dactyl long, arched, with a tooth one-third the distancefrom | 
the proximal end. Fingers widely gaping when closed. The fingers  —__ 
are exceedingly variable. Sometimes there are from one to three small | 
irregular teeth or tubercles on the pollex half way to the end. Some-  — 
times there are a few minute teeth on the dactyl instead of one large i 
one. In some of the females and smaller males the dactyl is little | 
arched and the gape is slight. - ; i 
Ambulatory legs spiny and hairy above, propodal joints slightly 
hairy below, dactyls equally hairy above and below. 
It is the rule that the smaller the specimen the more prominent the 
protuberances, the sharper the teeth and spines. Small specimens 
have the meral spines acuminate and occasionally two tubercles on the 
carpus near its posterior margin. 
