the Institute of Fisheries Research Laboratory 

 have been taken in this manner. Specimens have 

 also been taken from baited plots set for capture 

 of blue crabs, and in trawls from the oceanic 

 littoral. Surface to 28 fathoms. 



Type locality.— "The Southern States." 



Known range. — Cape Lookout, N.C., to Yuca- 

 tan, Mexico; Bahamas; Cuba; Jamaica. 



Remarks. — The genus Menippe has a fossil 

 record in North America dating from the Cretace- 

 ous, the thick, hard exoskeleton no doubt enhanc- 

 ing its chances of fossilization. The record for 

 M. mercenaria dates from the Pleistocene (Rath- 

 bun, 1035). 



Ovigerous females have been taken from May 

 to July (perhaps August) in North Carolina. 

 Binford (1912) discussed spermatogenesis and 

 fertilization in the species and gave notes on 

 spawning habits. Porter (1960) reviewed litera- 

 ture on fecundity and larval development of M. 

 mercenaria and described zoeal stages reared in 

 the laboratory. Females have been observed to 

 molt, then mate immediately after spawning in 

 the laboratory, and produce a new sponge a week 

 after the previous egg mass has hatched. Sub- 

 sequent to such mating, more than one mass of 

 eggs may be produced before another molt or mat- 

 ing occurs. Females have been known to produce 

 six egg masses in 69 days, each mass containing 

 between 500,000 and 1 million viable eggs. 



Porter described one prezoeal and six zoeal 

 stages for larvae reared in culture on Artemia 

 nauplii, but the prezoeal and sixth stages were 

 considered as probably atypical. Length of larval 

 life was approximately 27 days under the condi- 

 tions imposed, and from experimental data it was 

 concluded that warm water of high salinity is 

 needed for optimum survival. 



Manning (1961) gave data on relative growth, 

 showing that the juveniles have a relatively 

 broader front than adults. Both he and Wass 

 (1955) pointed out the superficial resemblance 

 of young M. mercenaria to Panopeus herbstii and 

 Eurytium limosum. and Manning gave distin- 

 guishing characters for each species at compara- 

 ble sizes. Further, the stridulating mechanism 

 was shown not to be visible in small specimens 

 and, indeed, stridulation itself has not been ob- 



served in the adults (Guinot-Dumortier and 

 Dumortier, 1960). 



In studies on the relationship of number and 

 volume of gills to oxygen consumption, Pearse 

 (1929) and Ayers (lOi'.S) found this form, along 

 with other mud crabs, intermediate between the 

 sluggish common spider crab and the more active, 

 partially terrestrial, fiddler and ghost crabs. 

 Pearse also found that M. mercenaria could with- 

 stand considerable dilution of the environment 

 with fresh water. Gray (1957) found gill area 

 per gram of weight to be intermediate in an array 

 of species ranging from land to shallow-water 

 habitats. 



Menzel and Hopkins (1956) found the stone 

 crab in Louisiana to be an active predator on 

 oysters. The powerful crabs killed small and 

 large oysters alike. Though predation was 

 found to be lowest in winter and highest in fall, 

 the average rate of consumption in the area 

 studied was 219 oysters per crab per year 

 ( = 1,000 bushels of oysters per acre if this num- 

 ber were available) . 



Genus Glyptoxanthus Milne Edwards, 1879 



Rathbun. 1930a. p. 263. 



Glyptoxanthus erosus (Stimpson) 



Figures 167. 183A 



Actaea erosa Stimpson. 1859. p. 51. 



Glyptoxanthus erosus: Rathbun. 1930a, p. 263. pi. 107 (rev.). 



Figure 167.— Glyptoxanthus erosus (Stimpson). Animal 

 in dorsal view, detail shown on right side, 5 mm. indi- 

 cated. 



MARINE DECAPOD CRUSTACEANS OF THE CAROLINAS 



185 



