Procamrarits, a Nf.w Subgenus. 441 



mm., al)domen, 25 mm., length of hand 13 mm., of pahii 7 mm., of 

 fingers 6 mm. 



The specific name is given in honor of the discoverer, Mr. E. B. 

 Williamson. Before Mr. Williamson started for Guatemala, I called 

 his attention to the possible j^resence of a Canibanis in this country, 

 and his search was rewarded by the discovery of this species. 



Remarks on the Geographical Distririttion. 



The existence of a Caiiihanis in Guatemala (C'oban, Alta Vera 

 Paz) was first mentioned by Huxley (1878), but the species has 

 never been described. It remains doubtful whether the present 

 species is the same, since it comes from another part of the country, 

 although both localities belong to the Atlantic slope. 



Caiiibariis luilliamsflni is sharply distinguished from all other species 

 of the genus, although it forms a natural group (subgenus Procamhanis^ 

 with three other species, two of which are found in Mexico {iiiguefi, 

 mexicaniis), and the third in Cuba (ciibcnsis^. The most closely 

 allied form is C. inexicaui/s, but this is apparently more highly 

 specialized, as is shown by the lack of the marginal spines of the ros- 

 trum and the lateral spines of the carapace. Thus C. li'illiainsoni is 

 to be regarded as a rather ])rimitive form, and stands between C. dig- 

 ueti and C. mexicaniis. I have regarded C. digueti as the most primi- 

 tive form of the whole genus ; but second to it is C. williamsoni. C. 

 mexicaniis comes very close to the latter, while C. cubcnsis is more 

 remote from the rest on account of the broadly dilated inner face of 

 the male organs ; but the beginning of the development of this feature 

 is clearly indicated in the other three species. 



Thus it is beyond doubt, that C. ciibensis points in its affinities to 

 Guatemala and Mexico, and our Guatemalan species indicates the 

 way by which Cuba was populated. In my paper referred to {Proc. 

 Am. Phil. Sor., 49, 1905), I have already assumed this connection 

 on the map, without knowing anything of the existence of C. 7cn/- 

 lianisoni, and this assumption has been fully confirmed by the dis- 

 covery of this species. 



The subgenus Procambariis appears to be the earliest type of the 

 genus, and its range is in the original home of the genus (Mexico and 

 Guatemala), with the exception of C. ciibensis, which apparently is 

 an early emigrant. 



The separation of the subgenus Procambariis from the rest of the 



