Width of areola 

 Length of chelcc 

 Width » 



ö EINAR LÖNNBERG, CAMBARIDS FROM FLORIDA. 



Leiigth of rostrnni _ 



Basal width of rostrum , 



Distance from tip of rostrum to cervical groove 



» » cervical groove to hindmargin of carapax - 



I IV' o mm. 



h " > 



1 19 mm. 



US ) 



1 5 mm. 



U > 



From the above it is plain that Caniharus acherontis is 

 a well-detiiied species, that does not sliow any likeness to any 

 of the blind Cambari hitherto known. Two questions may 

 now be asked which are not either so easily answered. How 

 great is the geological or phylogenetic age of this blind form 

 and which are its normal-eyed ancestors? To answer the 

 tirst (piestion about the age we have to try to lind ont how 

 (jld the subterranean water is in whieh it exists. The little 

 rivulet and its cavern can not have been formed before the 

 land had been raised above the level of the sea, and even 

 supposing it had been previously upheaved and eovered by 

 the sea again, the maximum age of the crayfish must in any 

 oase be reckoned from the last time it was eovered by the 

 sea. For even if in a foregoing period the cave had been 

 formed, the crayfish could not have lived below the sea. Thus 

 the uppermost marine layer will give us the maximum age 

 of tlie little cavern and the Cambarus. The phosphatelayer 

 in which were found sharks-teeth is the uppermost layer con- 

 taining fossils, and it is of course marine. Its age? It is 

 certainly tertiary and probably pliocene. But the sand and 

 clay deposited on the top of the phosphate layer have pro- 

 bably also a marine origin, but this (piestion does not seem 

 to be fully solved yet. An(JEL0 Heilprin says in his (9) 

 'Explorations on the Westcoast of Florida> (Wagner free Inst. 

 of Science, Philadelphia 1887) p. 66: »Freshwaterstreams, and 

 consequently dry land existed in the raore southern part of 

 Florida during the Pliocene period > But it can not 



