344 ORTMANN — DISTRIBUTION OF DECAPODS [April 3, 



In subsequent times, at the beginning of the Tertiary, the Carib- 

 bean Sea must have existed, since Tertiary deposits are largely 

 developed in this region, not only on the Antilles but also on the 

 Isthmus of Panama. It seems that in the beginning of the Tertiary 

 the old Antillean continent was divided into two main sections — 

 the Greater Antilles with Honduras and Guatemala to the north, 

 and the coast range of Venezuela to the south. The remnants of 

 this continent in the Greater Antilles and Central America re- 

 mained first in a large part land, bat apparently they were subject 

 to various changes during the Tertiary period and subsided and 

 were elevated repeatedly. 



We have seen that the geographical distribution of certain fresh- 

 water Decapods demands in the first line a connection of the 

 Greater Antilles with Mexico, and according to the foregoing con- 

 siderations this connection can have been situated only in the 

 direction over Honduras and Guatemala. We have further seen 

 that a Mesozoic connection of these parts is very likely, and that 

 the connection of Venezuela with Central America existed almost 

 up to the end of the Cretaceous. As we shall see below, we have 

 reason to believe that the freshwater crabs reached Venezuela in the 

 second half of the Cretaceous, and consequently it was also possible 

 for them to extend during this time into Central America (and 

 Mexico). If the latter parts were then or later connected with the 

 Greater Antilles, this would account for the presence of the most 

 primitive genus of the subfamily, Epilobocera, in these islands. On 

 the other hand, Potamobiida were probably present at the end of 

 the Cretaceous times in western North America. These parts were 

 connected with Central America in this period, Mexico being dry 

 land, and thus there was also a chance for the Potamobiidce (repre- 

 sented here by Cambarus) to reach finally the Greater Antilles. 

 Therefore we reach the conclusion that the first immigration of 

 freshwater Decapods into the Greater Antilles, represented by 

 Epilobocera, belongs to the end of the Cretaceous or the beginning 

 of the Tertiary, and that Cambarus cubensis possibly also belongs 

 to it; but since this form is a true Cambarus, although a primitive 

 one, I should prefer to put its immigration rather in the Tertiary 

 than in the Cretaceous. 



rated from Texas by the Antillean continent, while the Upper Cretaceous of 

 Western Ventzuela shows close affinity to Texas, the Antillean continent having 

 disappeared. 



