SPERM-TRANSFER ORGANS IN CAMBAROIDES. 269 







As elsewhere shown ' some of the Peruddae as well as the 

 lobsters have sperm receptacles whence we may infer that a 

 sperm receptacle was common to the ancestors of the crayfish. 

 In such case the absence of sperm receptacle in Astacns would 

 be due to loss, and the presence in Canibarus to retention of the 

 ancestral mode of sperm transfer. If we suppose that the resem- 

 blances and differences of organisms are connected with chance 

 variations it seems more likely that organs may have been inde- 

 pendently lost, in separate animals, than that the same organ 

 should have been independently acquired in separate organisms. 

 We would then say that Cambaroides and Cambams are closely 

 related as both have retained the hooks and the general form of 

 stylets of some ancestor but that Astacus and Cambaroides are 

 not so closely related though both have independently lost the 

 sperm receptacle while changing the form of stylets. 



Adopting Ortmann's views as to the origin of the present dis- 

 tribution of crayfish we would modify it chiefly by the assump- 

 tion of two migrations from Asia into America. We would think 

 of ancestral Asiatic crayfish with many gills and a sperm recep- 

 tacle of some sort filled by some use of the abdominal limbs. 

 One set of descendants retaining more gills but losing the sperm 

 receptacle became the Astacns of America and Europe as well as 

 the crayfish of the southern hemisphere. While another set of 

 descendants became Cambarus and Cambaroides. Part of this 

 branch migrated into America and ultimately, in Mexico accord- 

 ing to Ortmann's evidence, became the present Cainbarus with 

 reduced gills and highly specialized receptacle and stylets. The 

 other part remaining in Asia independently lost the receptacle but 

 retained the larger number of gills as well as the hooks. 



We might then find in Cambaroides indications of the former 

 presence of a sperm receptacle. As such we regard the hooks 

 that have no known use except as aids for the filling of a recep- 

 tacle. As such we regard the presence of ligula, spatula and 

 canula at the tip of the stylet. 



The absence of a tubule in the stylet, its clumsy form and the 

 reduced prominence of its tip as well as the simplicity of the 

 triangle of the second stylet might also be regarded as signs of 

 degeneration. 



Zoo/. Anzeigtr, 1909. 



