ASTACIDjE. 23 



and there is no membraneous hole, as the three lobes are closely 

 approximated ; the vasa deferentia are also stronger, more curved, and 

 have greater length than the body. Their end is visibly more dilated 

 than in Cambarus acittus. 



In the second-form male of Cambarus acutus the testicles are similar 

 but smaller, the superior lobes narrower, oval ; the inferior lobe is 

 acuminated, narrower, and not bigger than the connecting hole of the 

 superior lobes. The vasa deferentia are shorter. The microscopic ex- 

 amination of the contents of the testicles offers no further argument, as 

 the specimens have remained too long in alcohol. 



Of C. virilis. Tab. II. Figs. 128-132. — In the first-form male of 

 Cambarus virilis, 3.2 inch long, the testicles are somewhat similar, but 

 longer, being in length 0.7 inch. The superior lobes have a prismatic 

 form, with diverging acuminated ends. The prismatic part is exca- 

 vated above, and much separated from the smaller and compressed 

 hole. The inferior lobe is long and compressed, seen sidewise, oval, 

 and truncated behind. The vasa deferentia are longer than in Camba- 

 rus acutus, while their ends are not visibly dilated. 



In the second form of Cambarus virilis, 2 inches long, the testicles are 

 shorter, the superior lobes prismatic, but the superior part is not much 

 separated ; the inferior lobe is shorter, beginning with a narrow hole, 

 laterally more compressed; the vasa deferentia are shorter and nar- 

 rower. 



Of C Bartonii. Tab. II. Figs. 135-138. — In the first form of the 

 third principal group in Cambarus Bartonii, 2 inches long, the sexual 

 parts are more similar to those of Astacus fluviatilis. They are 3.5 

 inches long, the superior lobes oval and large, while their superior tip is 

 a little contracted. Connected by an inferior, well-separated, smaller 

 membraneous hole with the equally long hole of the inferior lobe, there 

 is to be found behind the connecting joint an inflated tubercle, while 

 lower down there is another which is similar but smaller. The inferior 

 lobe is pyriform, inflated behind, somewhat compressed laterally. The 

 vasa deferentia are stronger and longer, the ends being visibly dilated. 



In the second-form male of Cambarus Bartonii, 2 inches long, the 

 testicles are shorter, the superior lobes more trigonal, the inferior nar- 

 rower, elongated, much more compressed, acuminated behind, the 

 connecting holes not so well separated and finished, without tubercles 

 behind, while the vasa deferentia are narrower and shorter, the ends 

 not being visibly dilated. 



I may remark, that in the first-form males of Cambarus acutus and 

 Bartonii the three lobes of the testicles exhibit the same granulated 

 contents as in Astacus fluviatiUs. But in Cambarus virilis they are white 

 and have a fatty appearance, similar to those always found in the second- 

 form males. 



