extreme excitement, the major cheliped may be 

 rapped against the ground in a flexed position. 



Burkenroad (1947b) observed a drumming 

 sound produced by males vibrating their large 

 cheliped just outside the burrow at night, or in 

 daytime just after waving and retreating into the 

 burrow. Pearse (1914) was never able to ob- 

 serve copulation in the field following display, but 

 did observe five matings of captive pairs in the 

 laboratory. Females mated in the "hard shell'' 

 condition. 



Color changes in U. pugilator have been in- 

 vestigated extensively in recent years. Carlson 

 (1937) contended that the chromatophores re- 

 spond to humoral control by the sinus gland in 

 the eyestalks. Brown and Sandeen (1948) and 

 Brown and Webb (1948) showed that there is a 

 rhythmic secretion of hormone which operates to 

 disperse the black and white pigments in the day 

 and concentrate these at night. Superimposed on 

 these responses are responses to background color, 

 to total illumination, and to temperature, such 

 that both pigments tend to disperse as intensity 

 of illumination increases; but black pigment tends 

 to concentrate as temperature increases above or 

 decreases below about 15° C, and white pigment 

 tends to disperse as temperature is increased above 

 or decreased below about 20° C. Such lightening 

 or darkening has been recorded in the field by a 

 number of observers. Brown (1950) extended 

 Carlson's work on red chromatophores, giving evi- 

 dence for the activating principles and their daily 

 rhythmicity. Further experiments with black 

 chromatophores (Webb, Bennett, and Brown, 

 1954) showed that the diurnal rhythmic darken- 

 ing and lightening are independent of structures 

 in the eyestalks and that a substance which con- 

 centrates black pigment participates in regulation 

 of the chromatophore system. Guyselman (1953) 

 described a series of five color changes or stages 

 which occur during the premolt period of normal 

 animals. He found (as suggested earlier by 

 Abramowitz and Abramowitz, 1940) that the 

 sinus gland-X organ complex plays a role in regu- 

 lation of metabolism of water and inorganic con- 

 stituents. Evidence of a diurnal rhythm of water 

 uptake was presented. Fingerman (1956) showed 

 that even in the Gulf of Mexico, where tides are 

 daily, the persistent rhythmic color changes re- 



main scheduled as they are in crabs living where 

 tides are semidiurnal, but (1957) that for a given 

 local area the phase may be slightly altered ac- 

 cording to the time that the burrows are uncov- 

 ered by a receding tide. 



Extending their investigations on rhythmicity, 

 Brown, Webb, Bennett, and Sandeen (1955) 

 showed that oxygen consumption in both U. 

 pugilator and U. pugnax shows apparent persist- 

 ent trends related to solar and lunar cycles. 



As a sidelight to work with eyestalkless U. 

 pugilator, Brown and Jones (1949) found that 

 removal of eyestalks from adult females resulted 

 in a period of rapid ovarian growth, with accom- 

 panying increase in oocyte diameter and a color 

 change of the ovary from light pink to deep 

 purple. Eggs produced by such animals failed to 

 become attached to the pleopods. 



The subject of intersexuality and relative 

 growth was reopened by Darby (1935) as a re- 

 sult of examination of some 9,000 specimens of 

 U. pugilator collected at Beaufort, N.C. Among 

 these, 12 females were obtained with 2 fiddles, but 

 no female was found in 1 large chela. These 12 

 specimens had fully widened, typically female 

 abdomens and were always found feeding with 

 the males in contrast to the other small-clawed 

 females which stayed close to their holes. Darby 

 termed these female-to-male intersexes. A male- 

 to-female intersex; that is, a crab with a typical 

 male abdomen and normal reproductive append- 

 ages, yet with small claws, was found only once, 

 at Charleston, S.C. Because feeding is accom- 

 plished with the small claw, even partially sym- 

 metrical males must be handicapped in obtaining 

 food, and it is not surprising that perfectly sym- 

 metrical adults do not, or rarely, occur. Darby, 

 thus, refuted the arguments of Huxley and Rath- 

 bun that females with narrow abdomens were 

 merely extremes in the normal variation curve for 

 female abdomen growth, and supported the con- 

 tention of Morgan that these were truly intersexes. 



Superfamily Oxyrhyncha 



Carapace more or less narrowed in front, and 

 usually produced to form a rostrum; branchial 

 regions considerably developed, hepatic regions 

 small. Epistome usually large; buccal cavity 

 quadrate, with anterior margin usually straight. 



MARINE DECAPOD CRUSTACEANS OF THE CAROLINAS 



235 



