834 General Notes. [ October, 
It was the intention of the writer to examine into the geologi- 
cal succession of the crayfishes, but since the specimens were 
received for examination, the excellent and thorough work of 
Professor Huxley, entitled “ The Crayfish,” has appeared, and his 
inquiries into the geological succession and probable genealogy 
of the existing crayfish, completely cover the ground. We wi 
condense the statements of Professor Huxley, in order that the 
reader may see the interest to.be attached to the discovery of the 
Wyoming fossils. 
While the shrimps or Macrura date back to the Carboniferous, 
fresh-water types existed in the fresh-water beds of the Wealden. 
n the marine deposits of the Cretaceous epoch, however, astaco- 
morphous forms, which are known by the generic names of Hop- 
loparia and Enoploclytia, are abundant. 
“In the chalk of Westphalia (also a marine deposit) a single 
specimen of another Astacomorph has been discovered, which pos- 
sesses an especial interest, as it is a true Astacus (A. politus yon 
der Marck and Schluter), provided with the characteristic trans- 
versely divided telson which is found in the majority of the 
Potamobiide. * * * } 
‘If an astacomorphous crustacean, having characters interme: 
diate between those of Eryma and those of Pseudastacus, existed 
in the Jurassic epoch or earlier; if it gradually diverged into 
Pseudastacine and Erymoid forms; if these again took on 4 se 
cine and Homarine characters, and finally ended in the existing 
Potamobiidz and Homarina, the fossil forms left in the track 0 
this process of evolution would be very much what they actually 
all the 
known facts are in harmony with the requirements of the wher 
primitive astacomorphous form.”—(The Crayfish, p. 341-340 ~ 
It will thus be seen that the discovery of an apparently ire 
water Cambarus in the Green River beds of Western Wyom!ng» 
