FOSSIL CRUSTACEANS. 
388 
A rich harvest, therefore, remains in store for the 
Naturalist who will trace this interesting subject 
through the entire series of Geological formations. 
The analogies between existing species, and 
certain fossil remains of Crustaceans have been 
beautifully illustrated by the investigations of 
M. Desmarest. From him we learn, that all the 
inequalities of the external shell in the living 
species have constant relation to distinct com- 
partments in their internal organization. By the 
application of these distinctions to fossil species, 
he has pointed out a method of comparing them 
with living Crustaceans in a new and unexpected 
manner, and has established satisfactory analo- 
gies between the extinct and existing membeis 
of this very numeroiis Class, in cases where the 
legs and other parts on which generic distributions 
have been founded, were entirely wanting.* 
Beferring my readers to these valuable com- 
* H. Von Meyer has recently noticed five or six extinct 
genera of Macronrous Decapods in the Muschel-kalk of Ger- 
many. (Leonhardt and Broun Jahrbuch, 1835.) 
The subject of English fossil Astacids (^Crawfishes) is at this 
time receiving important illustration in the able hands of Prof- 
Phillips. 
In a recent communication to the Geological Society (June 
10, 1835), Mr. Broderip describes some very interesting remains 
of Crustaceans from the Lias at Lyme Regis, in the collection of 
Viscount Cole. In one of these, the Lamellae of the externa 
Antennae, the form and situation of the eyes, and other characters 
show that it was a macraurous decapod intermediate between 
Palinurns and the Shrimps. 
A fragment of another macronrous decapod proves the exist 
