IV 



TEMPORARY HERMAPHRODITISM 



103 



This is well exemplified in the case of the ordinary males of 

 Inach'us mauritanicus, of some other Oxyrhynehous crabs, and 

 of the Crayfish Cambarus. 1 During the breeding season the males 

 of /. mauritanicus fall into three chief categories : Small males 

 with swollen chelae (Fig. 73, A), middle-sized males with flattened 

 chelae (B), and large males with enormously swollen chelae (C). 

 On dissecting specimens of the first and third categories it is 

 found that the testes occupy a large part of the thoracic cavity 

 and are full of spermatozoa, while in the middle-sized males 



FIG. 73. - Intii-liiix iiKuti-iliiiiicnx, ,: 1. A, Low male ; B, middle male ; C, high 

 male ; the great chela of the right side is the only .ippend;t;_;v represented. 



with female-like chelae the testes appear shrivelled and contain 

 few spermatozoa. These non-breeding crabs are, in fact, under- 

 going a period of active growth and sexual suppression before 

 attaining the final state of development exhibited by the large 

 breeding males. This phenomenon is obviously parallel to the 

 "high and low dimorphism" 2 so common in Lamellicorn beetles, 

 where the males of many species are, divided into two chief 

 categories, viz. "low males" of small size in which tlie 

 secondary sexual characters are poorly developed, and "high 

 males" of large si/e in which these characters are propor- 



1 FMXUM, Ann. Mfnj. .Vr//. Hist. (:"), xiii., 1884, p. 117. 

 - C. Smith, Mini,. /<!. Stat. Neapel, xvii., lOOf., p. 



