No. 636] SHORTER ARTICLES AND DISCUSSIOX 



81 



ture female fiddlers showing different widths of abdomen normal 

 to the growing female in passing from the juvenile or immature, 

 to the sexually mature, condition. However, this exhibit ap- 

 parently had the opposite effect from that intended, as Pro- 

 fessor Morgan pronounced them all "intersexes" and thereby 

 seemingly robbed the female fiddler of its period of adolescence. 



In his paper "Variations in the Secondary Sexual Characters 

 of the Fiddler Crab"^ we find Professor Morgan's exposition 

 of the subject. It is not easy to follow the author owing (1) to 

 erroneous or incomplete references to figures and (2) to ab- 

 sence of measurements; for example, "Fig. 45",'' cited on p. 

 225, line 12, does not exist, "Fig. 45'," p. 225, line 3, is cited 

 as a female abdomen when it is really a male, and one can not 

 tell if the two unequal chelae of Fig. 4A belong to one individual, 

 which is probable, and if the two unequal chelfe of Fig. 4B be- 

 long to one individual, which is probable but not possible, as the 

 text says that they are "of the same size." There are no meas- 

 urements nor indication of enlargement of figures. 



The ease under discussion belongs in Professor Morgan's 

 second category of intersexes. He tells us that tlip specimens 

 are always small, that they are female in character except for 

 the abdomen being narrower than in the mature female, and 

 the abdominal appendages being different from those of the 

 mature female but not at all malelike. Why, one naturally asks, 

 are they not juvenile? His reply is. "because normal individuals 

 of the same size have the abdomen full width." This argument 

 unsupported is fallacious. 



Many species of crabs are known to attain sexual maturity 

 at a much smaller size than their maximum and to exhibit con- 

 siderable range in the size at which they att^iin that maturity. 

 As an example, two jars full of the common shore-crab of the 

 Pacific coast, Hemigrapsus midiis, show egg-bearing crabs rang- 

 ing in width of dorsum from 10.4 mm. to :V2 mm., and among 

 the immature females with nari-ow abdomens, six individuals 

 which range from 12.5 to 15.7 mm. in width. 



Professor Morgan goes on to say that some of tlie smallest 

 "intersexes" have the narrowest, abdomen, that there is no 

 obvious relation between tlie size of the crab and tlie rolaHve 

 width of the abdomen, but that there is some correlation liotwoen 

 the character of the abdominal appendages and the width of the 

 1 Amer. Nat., Vol. LIV, No. 632, May- June. 1920, pp. 220-246. 



