iv TEMPORARY HERMAPHRODITISM 103 
This is well exemplified in the case of the ordinary males of 
Inachus mauritanicus, of some other Oxyrhynchous crabs, and 
of the Crayfish Cambarus.' During the breeding season the males 
of LZ. 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 
Fia. 73.—Inachus mauritanicus, x 1. A, Low male; B, middle male ; C, high 
male ; the great chela of the right side is the only appendage 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 ”? 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 the 
secondary sexual characters are poorly developed, and “high 
males” of large size in which these characters are propor- 
1 Faxon, Ann. Mag. Nat. Hist. (5), xili., 1884, p. 147. 
* G. Smith, Mitth. Zool. Stat. Neapel, xvii., 1905, p. 312. 
