120 Scientific Intelligence. 
tains only two — Callianidea, Edw., and Isea, Guerin: the last 
name was changed by Edwards to Callianisea’; but as this word is so 
near Callianassa oe Callianidea, a contraction to — would be 
preferable. 
Subtribe 2. Astacidea.—In this subtribe we adopt De “Hino? § sec: 
a that we exclude the Megalopidea, and we do not associate 
e Thalassinidea with the Astacidea. The sections or —_— ra 
Sopllarides Palinuride, evade, and Astacide,. ° zg 
Leach in 1819 subdivided the old genus ‘Astacus, naming tie mar rine 
species a. Edw.) Astacus,and the fresh water (Astacus, Edw.) 
maar ius. Edwards’s division, of like character, now generally ac- 
digs ted, was not See till 1837. Awwieaees hence cm the srs 
pulsed _ 1850, but not in the seapatr Calshagies of 1847. 
Caridea.—In arranging the aridea into groups, much 
stress is lab laid upon external ‘form and ‘os th of beak. The un- 
importance of these characters is inferrible from the fact that they in- 
Hypp 
A erk he are other characters of more fdemennl value ; and these 
have been brought forward by De Haan. ‘The man dibles afford the 
distinctions alluded to. In one section they are very slender and are 
bent nearly at a right vane without enlargement at the crown. : 
another me are very stout, and somewhat bent above with a broad di- 
lated crown. Io a third, sree are stout, but not bent, and have @ 
dented summit. In a fourth they have, in addition to a projec cling 
lateral crown, a large summit process, which is often oblong and very 
— These forms are ee of different sections of 
The fact that the mandibles bear a dips or not is of much less im 
rtance ; for the portion of the mandible which is most essential to its 
functions is the crown. mong the Paleemonine, there are genera 
ving a mandipular palpus, and others without one ; while the tW? 
kinds in other respects are remarkably close in their paar sn 
have found moreover, that in this group, the length of the palpus 
ries with the ins of the 2d and 3d flagella of the inner Hee 
if u are sree to their bases nearly, (as datichagr | ae 
