438 Annals of the Carnegie Museum. 



Thus, from my subgenus Cainbants, certain species are removed as 

 the subgenus Procambanis, which would belong to Faxon's second 

 group : but not the whole of Faxon's second group belongs to Pro- 

 cambanis, since the other species, which I have designated (/. c.') as 

 the sifiii//ans-gYO\.\\> and the section of C. gracilis, possess sexual 

 organs that entirely correspond to those of the section of C. olandingi. 

 In the subgenus Cai/ibanis, consequenth^ three sections remain : 



Section of C. siviitlaus : 



Male with hooks on third pereiopods. Areola rather narrow, but 

 never obliterated in the middle, slightly longer than half of the ante- 

 rior section of the carapace. Chelae elongated and subcylindrical. 



Species : siiiii/lans, gallinas. 



Section of C. gracilis : 



Male with hooks on third pereiopods. Areola obliterated in the 

 middle, considerably longer than half of the anterior section of cara- 

 pace. Chelae short, broad, ovate. 



Species : gracilis, kage/iia/iiis, advena. 



Section of C. blandingi : 



Male with hooks on third and fourth pereiopods. Areola wide, or 

 narrow, rarely obliterated in the middle, shorter, or longer. Chelae 

 generally elongated, narrow and subcylindrical. 



Divided into four groups, containing together about 15 species. 



The species of the subgenus Procambarus are easily distinguished 

 by the following characters : 



Oy Inner face of male se.xual organs flattened, but not broadly dilated. 



by Sexual organs of male slightly curved backward at apex ; horny spine of 

 inner part straight, situated posterior to the tip of the outer part. Rostrum 

 carinated above. Carapace with one lateral spine on each side. 



C. (^Procambarus^ digiieti Bouvier. 



b^. Sexual organs of male straight ; horny spine of inner part curved, situated 



anterior to the tip of outer part. Rostrum not carinated above. 



Cy Rostrum with marginal spines. Carapace with two lateral spines on 



each side. C. [Proiaiitbatus) wiliiaiiisoni f^-p^c. nov. 



c^. Rostrum without marginal spines. Carapace without marginal spines. 



C. [Procambarus) mexicamis Erichson. 

 rt.^. Inner face of male sexual organs flattened and greatly dilated, forming a broad, 

 flat, setose plate. Rostrum not carinated, with marginal spines. Carapace 

 without lateral spines. C. [Procainbarits) cubensis Erichson. 



