Section Brachyura 



Crabs with abdomen much reduced in size, 

 straight, symmetrical, closely bent under thorax, 

 never used for swimming, and with uropods rarely 

 present, never biramous. Cephalothorax de- 

 pressed, fused with epistome at sides and nearly 

 always in middle. Antennal scales immovable. 

 Third maxillipeds broad. First pair of legs che- 

 late and nearly always much stronger than other 

 legs. 



Subsection Gymnopleura 



Anterior thoracic sterna broad, posterior tho- 

 racic sterna narrow and keellike. Posterior tho- 

 racic epimera largely exposed by reduction of 

 branchiostegite. Female openings on coxae. Last 

 pair of legs dorsal in position, normal or reduced 

 in size. Sternal canal present. Thoracic nerve 

 ganglion-chain elongate. Antennary sternum tri- 

 angular, spout-shaped. Branchiae eight on each 

 side (Bourne, 1922). 



Family Raninidae 



Crabs with carapace remarkably elongate but 

 not covering abdominal terga, first four or five 

 terga lying exposed in dorsal plane of body. Last 

 pair of legs also raised in dorsal plane of body. 

 Antennae and antennules large, not folding into 

 fossettes. Vasa deferentia protruding through 

 bases of fifth pair of legs; oviducts piercing coxa 

 of third pair of legs. Sternum broad anteriorly, 

 narrow or linear posteriorly. A pair of respira- 

 tory orifices between tergum of first abdominal 

 segment and coxae of last pair of legs. External 

 maxillipeds completely covering buccal cavity, 

 with palp concealed in repose; exopodite but little 

 longer than ischium. Gills less than nine in num- 

 ber on either side. Hand flat, immovable finger 

 extremely bent allowing movable finger to close 

 against anterior border of hand. (Modified after 

 Alcock, 1896, and Rathbun, 1937.) 



Genus Ranilia H. Milne Edwards, 1837 



Rathbun, 1937, p. 17. 



Ranilia muricata II. Milne Edwards 



Figure 117 



Ranilia muricata H. Milne Edwards, 1S37, p. 196.— Hay and 

 Shore, 1918, p. 420. pi. 31, flg. 1.— Rathbun, 1937, p. 18, pi. 3, 

 figs. 8-6 ; pi. 4, figs. 1-4 (rev.). 



Figure 117. — Ranilia muricata H. Milne Ed- 

 wards. Ovigerous female in dorsal view, 

 first to fourth legs of right side shown, only 

 fifth leg of left side shown, 5 mm. indicated. 



Recognition characters. — Carapace oval, 

 strongly convex from side to side, slightly so 

 from front to back, smooth posteriorly but with 

 numerous transverse ciliated wrinkles anteriorly. 

 Rostrum slender ; anterior border of carapace with 

 four strong spines on each side, innermost over- 

 hanging base of orbit, third surmounting exter- 

 nal angle of orbit, fourth at external angle of 

 front. Eyestalks strong, about four times as long 

 as rostrum, and capable of being turned back into 

 deep, oblique orbits. Antennules small. Antennae 

 directed forward, slightly longer than eyestalks. 



First pair of legs subchelate, stout, flattened 

 distally, squamous-denticulate above, with a 

 strong spine on superodistal margin of merus, 

 carpus, and hand ; distal margin of hand perpen- 

 dicular, toothed; dactyl strong, curved. Second, 

 third, and fourth pairs of legs with flattened, tri- 

 angular dactyls. Fifth pair of legs elevated, 

 turned forward, fringed with hairs. 



Abdomen short and narrow. 



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