422 
posable articulation. First three segments of abdomen, each 
bearing a pair of biramous, natatory feet ; remainder of abdo- 
men consisting of one very large trunk, supporting anteriorly a 
pair of large, foliaceous, lobed appendages, and a pair of cylin- 
drical false feet, and terminated posteriorly by two lamellar 
leaping organs, and an intermediate leaf-like lobe. 
1. C. terebrans, Philippi.— Last three pairs of thoracic feet 
with the terminal joint foliaceous. Hab.—Coast of Trieste. 
2. C. destructor, Mihi (provisional species).—All the tho- 
racic feet, except the first two, terminated by a small hooked 
claw. Hab.—lrish coast. 
The author, after entering into the details of the external 
anatomy of Chelurus, maintains the necessity of considering 
this genus as the type of a distinct family among the amphi- 
poda, assuming as the grounds of the assigned rank the remark- 
able condition of the posterior region of the abdomen, the first, 
second, and third ring of this region being consolidated into 
one great trunk, bearing three pairs of heteromorphous appen- 
dages. Availing himself, therefore, of the characters derived 
from these considerations, the families of amphipodous crusta- 
cea were analytically arranged as follows : 
Fourth and fifth abdominal segments conflu- } 
| ent ; abdominal appendages of the fourth and L Family. 
: fifth pair very different in form (Reteramor, CuEeLuRIDA. 
< phous). 
S | (Mouth  con- 
& J cealed by G 
1 Fourth and fifth abdominal / the maxil- ? 7AMMARID®- 
= segment distinct ; abdomi- lary feet. 
2 nal appendages of the fourth) Mouth _ not 
Hyperip#. 
in form (isomorphous). by the max- 
and fifth pair nearly similar concealed 
L illary feet. 
Dr. Allman also read a paper on a new Genus and Species 
of Entomostraca. 
The little animal which formed the subject of this commu- 
nication inhabits the branchial sac of Ascidia communis, in 
