Jersey (Rathbun, 1935) and Maryland (Easton, 

 1940). 



Ovigerous females are known to occur in spring 

 in North Carolina. 



Pearse (1929), studying the survival rates of 

 various estuarine crabs in dilutions of sea water 

 and in air, found L. dubia least able to survive 

 desiccation and dilutions of sea water. Ayers 

 (1938), in a study of the relationship of habitat 

 to oxygen consumption among certain estuarine 

 crabs, found that L. dubia lives much of the year 

 in .relatively deep [estuarine] water where there is 

 low oxygen content, sometimes very little. The 

 species is correspondingly sluggish and slow. Gray 

 (1957) showed that gill area per gram of weight 

 in this species is small. 



A peculiar association of this species with the 

 jellyfish Stomolophus meleagris has been reported. 

 The crabs have been found in the subumbrellar 

 space and on occasion small specimens have been 

 taken from the genital pits. Corrington (1927) 

 found medusae with crabs between Sullivans Is- 

 land and Isle of Palms, S.C., in May, and Outsell 

 (1928) found the association in the vicinity of 

 Cape Lookout, N.C., in summer and fall. The 

 crabs were found in adult jellyfish and varied in 

 length from 3 to 37 mm. 



Pearse (1952b) reported Octolasmis lowei 

 (=mt/Neri) on the gills and mouth parts, and 

 Chelonibia patula on the carapace of L. dubia in 

 Texas. 



Subfamily Mithracinae 



Carapace broadened anteriorly by outstanding, 

 often tubular, orbits; orbits formed (1) by an 

 arched supraocular hood, or semitubular horn, (2) 

 by a hollowed postocular process, and (3) by a 

 remarkable broadening, or by a prolongation, of 

 anterior part of basal antennal article, affording 

 complete concealment to retracted eye. Rostrum 

 often more or less deflexed (Alcock, 1895). First 

 pleopod like that in Pisinae; second pleopod short 

 ( Stephensen, 1915). 



KEY TO GENERA OF MITHRACINAE IN THE 

 CAROUNAS 



Modified after Garth (1958) 



tercalated orbital spine present (between supraor- 

 bital and postorbital spine) ; <>rl>its projecting sorne- 

 >nd general outline of carapace, but not 

 tubular. 



254 



b. Rostrum small ; carapace ovate, usually broader 

 than long Mithrax (p. 254). 



bb. Rostrum large, usually with two strong horns ; 

 carapace broadly pyriform ; basal antennal article 

 armed with a prominent spine at anteroexternal 



angle Microphrys (p. 259). 



aa. Intercalated orbital spine absent ; orbits tubular. 



b. Lateral margin of carapace armed with series of 

 strong spines ; basal antennal article very broad 



Strnocionops (p. 260). 



bb. Lateral margin of carapace not armed with series 

 of strong spines, but with a spine, usually strong, at 

 lateral angle of carapace Macrocoeloma (p. 263). 



Genus Mithrax Desmarest, 1823 



Garth, 1958, p. 352. 



KEY TO SPECIES IN THE CAROLINAS 



(Modified from Garth, 1958, and Rathbun, 1925) 

 a. Carapace roughened to greater or lesser extent by 

 tubercles or spinules, branchial grooves wanting ; inter- 

 mediate orbital teeth conspicuous, pointed, or sub- 

 truncate (Subgenus Mithrax). 



b. Hand armed above with spines or spinules. 



e. Two spines only on basal (fused) article of an- 

 tenna spinosissimus *(p. 254). 



cc. Three spines on basal (fused) article of antenna; 

 carapace paved with flattened granules, concealed 



by short hair verrucosus (young) (p. 255). 



bb. Hand not armed above with spines or spinules. 

 c. Carapace paved with close-set, tessellated gran- 

 ules verrucosus (p. 255). 



cc. Carapace not paved with close-set, tessellated 

 granules, 

 d. Gastric region without definite transverse row 



of five tubercles hispidus (p. 256). 



dd. A transverse row of five tubercles across gas- 

 tric region plcuracanthus (p. 257). 



aa. Carapace smooth and bearing oblique branchial 

 grooves, either strongly or weakly indicated ; inter- 

 mediate orbital teeth inconspicuous, tuberculiform 



(Subgenus Mithraculus). 

 Carapace broader than long ; anterolateral margins cut 

 into spines, or angular lobes, or spines and lobes ; four 

 anterolateral protuberances behind orbit 



forceps (p. 258). 



Mithrax (Mithrax) spinosissimus (Lamarck) 



Figures 234, 245A 



Maia spinosissima Lamarck, 1818, p. 241. 



Mithrax spinosissimus: Rathbun, 1925, p. 383, pi. 135 (rev.L 



Recognition characters. — Large. Carapace 

 nearly naked, subcircular, approximately as broad 

 as long; surface rough with short spines, those in 

 center blunt, elsewhere sharp; cervical suture 

 deep; hepatic and cardiac regions distinctly de- 

 limited. Rostral horns narrow, obliquely truncate 

 and granulate at extremity, separated by a U- 



FISH AND WILDLIFE SERVICE 



