120 Description of a new Irish Crustaceous Animal. 
Zoeci appears to me to have its proper position near to this 
genus, though apparently much wanting in the development of 
particular parts. If we could imagine the obliteration of the pos- 
terior segments of the body, or that the tail and anterior ring 
were so brought together, as to drive the intermediate rings 
under the anterior, and prevent every thing more than mere rudi- 
mentary portions of these rings to be traced, and the swimming 
feet alone with the other parts removed, we should then find re- 
maining parts or modified parts analogous to those of Zoeci. 
Thus, in the mouth, infinitely the most essential object for consi- 
deration, we should find, in the first place, a labium common to 
both, then three successive pairs of appendages performing ana- 
logous offices. The first pair (internal mandibles of Jurine) oc- 
cupy a similar position. The next in series marked in the deli- 
neations of Zoea (fig. 8) unquestionably perform functions similar 
to those marked (fig. 11, 12) in Anomalocera; and lastly, the 
lobate body, adjoining the legs of Zoea, has its analogous part 
in (fig. 18) Anomalocera, and lies horizontally appended by one 
corner, which is a singular confirmation of the views I am now 
taking. Fig. 14 of the Anomalocera may likewise be looked upon 
as replaced by the anterior division of the leg of Zoea, so that 
without any straining, an affinity between the animals may be 
traced. The antennae and eyes present the greatest sources of 
discrepancy, but not greater than is to be found in adjoining 
tribes, and indeed it is observable that, as we descend from the 
more highly organised species, greater diversities always occur in 
analogous parts not essential to the absolute existence of the ani- 
mal, the parts of manducation being almost the only parts which 
preserve a constancy of character. 
From an attentive consideration of the habits and forms of these 
minute animals, I should be much inclined to remove the whole of 
them from their present connection with the bivalve Lophyropoda, 
and allot them a much higher station in the system, in fact, to a 
position which is hinted at by Latreille, close adjoining Mysis of 
Fabricius, and forming from it a diverging branch nearly on a 
rank with Squilla, but not in the same series, for this latter is too 
intimately connected with the adjoining tribes to admit of being 
separated by these. I have just detected among those I brought 
with me from Mauritius, a species* which forms the transition 
from Squilla to the Amphipoda, and whose description I propose 
to present to the Society as an appendix to the present paper. 
* Zeuxo Westwood iana, Templeton. 
