OXYSTOMATOUS AND ALLIED CRABS OF AMERICA 215 



Fingers smoky horn-color, becoming blackish on upper side of dactyl. 

 Ambulatory legs yellow, finely reticulated with red lines. (A. E. 

 VerriU.) 



Variation. — The carapace varies in relative length and breadth 

 due to greater or less convexity; in size and prominence of dorsal 

 tubercles; and in distinctness of rostral teeth, some having four teeth, 

 others having no median sinus, or the lateral teeth slightly developed. 

 The variations do not correspond \\dth geograpliical regions. 



Measurements. — Male (66368, Bird Key Reef), extreme length of 

 carapace 49, width at sinus just in front of \vings 51.2, greatest width 

 of carapace 64 mm. 



Range. — ^Florida Keys to Bahia, Brazil; Bermuda; west Africa; 

 Red Sea and Persian Gulf; islands of Indian and Pacific Oceans; 

 beach to 120 fathoms. 



Material examined. — See table 70, page 216. 



Genus MURSIA Leach 



Mursia Leach, in Desmarest, Diet. Sci. Nat., voL 28, p. 231, 1823 (type not 

 mentioned). — Desmarest, Considerations gen^rales sur la classe de Crus- 

 taces, p. 108 (footnote), pL 9, fig. 3, 1825 (tj'pe "Mursie Mains-en-crete") . — 

 Latreille, in Cuvier, Regne animal, ed. 2, vol. 4, p. 39, 1829 (type not 

 mentioned). — Milne Edwards, in Cuvier, Regne animal (Disciples' ed.), 

 pi. 13, fig. 1, 1837 (type Mursia [Mursica, by error] cristata). 



Platymera Milne Edwards, Histoire naturelle des Crustaces, vol. 2, p. 107, 

 1837 (type P. gaudichaudii IMilne Edwards). 



Thealia Lucas, Ann. Soc. Ent. France, vol. 8, p. 577, 1839 (tj'pe, T. acanthophora 

 Lucas) . 



Carapace oval, moderately convex, rounded in front, rapidly 

 contracted behind, the evenly arched anterolateral margins ending in a 

 large lateral epibranchial spine. Front with a small acuminate tip. 

 Orbits large, oval, with a distinct fissure in upper margin and with 

 two deep gaps in lower margin in one of which rests the basal article 

 of the antenna. Eyes large, eyestalks short and thick. Antennules 

 fold obliquely; basal article of antennae not dilated. No distinct 

 epistome; endostome prolonged into a canal incompletely divided 

 longitudinally; first pair of maxillipeds have each a lamellar process 

 to complete the canal below. The external maxillipeds do not meet 

 across the mouth but expose the mandibles. Chelipeds enlarged 

 much as in Calappa but merus with merely a distal ridge with one 

 or more spines instead of a transverse crest. Palm with a dentate 

 crest less high than in Calappa. Chelipeds asymmetrical as regards 

 fingers, which on one hand have at base of prehensile edge a stout 

 lobule. Legs large, first two pairs at least as long as chelipeds. 

 Male abdomen with segments 3-5 fused; in both sexes the tergum of 

 first segment is entirely concealed and that of second strongly carinate 

 transversely. (After Alcock.) 



West coast of America to Japan and AustraHa. 



