132 E. A. ANDREWS. 



Comparing the annulus of Cambarus montezuma? with that of 

 other Cambari we see that though it departs so much in general 

 form yet it agrees in containing a sperm pocket that is both in 

 structure and use fundamentally identical with the sperm pockets 

 of other Cambari. In all cases known the male fills the inner 

 curves of the pocket with sperm and the outermost curve, near 

 the end into which the male pleopod is thrust, with a wax or 

 cement that seals the sperm in. 



The sperm pocket here described is strikingly like that pre- 

 viously described for C. immunis (9), both in the simplicity and 

 form of its bendings and in the fact that it runs transversely 

 instead of longitudinally as in most crayfish. Again the form of 

 the pocket here described agrees closely with that of C. clarkii 

 (9) though the latter is a longitudinal, median pocket. 



The sperm pocket of C. montezumce thus resembles the simplest 

 sperm pockets known, those most like an early stage of the more 

 specialized pocket of C. affinis, whose ontogeny has been described 

 elsewhere (10). 



As far as the sperm pocket is of any value in indicating phylo- 

 genetic affinity it points to the conclusion that C. montesumce is 

 not a highly specialized form, but need not be taken to mean that 

 there is any close relation between C. montesumcs and either C. 

 immunis or C. clarkii, which other characters indicate are remote. 

 And the value of similarity in form of the sperm pockets in these 

 three is nullified by their different positions on the annulus. The 

 ontogeny of the sperm pocket in C. affinis shows that it starts as 

 a median groove which secondarily has added to it the part right 

 or left of the median line and if this is the general rule for other 

 Cambari such wide departure from the median position as that 

 in C. immunis and C. montezumce may well mean remote connec- 

 tion with such a median form as that in C. clarkii and if the 

 ontogeny of the annulus in C. montezumcB were known the close 

 resemblance of its sperm pocket to that of C. immunis might 

 prove to be a superficial one. 



As yet of the six subgenera into which Cambarus has been 

 divided by Ortmann the sperm pocket has been made known in 

 four : in C. affinis, C. virilis, C. immunis, representing the sub- 

 genus Faxonius ; in C. bartoui, representing the subgenus Bar- 



