SUB-CLASS B EUCRUSTACEA—PHY LLOPODA 639 
Sub-Class B. EUCRUSTACEA. Kingsley. (Crustacea proper.) 
Crustacea not having the body divided into median and lateral lobes; with 
filiform, plumose, or lamellate gills in either thoracic or abdominal region , with two 
pairs of antennae, and with the maxillae and mandibles never pediform. Nauplius 
stage either free-swimming or passed in the egg. 
In the Crustacea proper the appendages of the cephalothorax are as follows: 
The first and second pairs are preoral and are known as the antennae, the 
third pair, placed at either side of the mouth, are the mandibles , the fourth 
and fifth pairs are secondary jaws, called mazillae. The appendages behind 
these vary in character, some being walking feet, while from one to three 
pairs may be subsidiary to the maxillae in eating, in which case they are 
called maxillipeds. 
The Luerustacea are commonly divided into Entomostraca and Malacostraca, 
but the first of these groups is not a homogeneous assemblage ; it is rather a 
division in which have been placed all forms not members of the Jalacostraca, 
the almost universal presence of a nauplius stage being its chief differential 
character. The Hucrustacea are here divided into the super-orders Phyllopoda, 
Ostracoda, Copepoda, Cirripedia, and Malacostraca. 
Super-Order 1. PHYLLOPODA. Latreille.' 
Ewcrustacea of elongated form, often with distinetly segmented bodies, usually 
with flat shield-shaped or laterally compressed carapace. 
Under the Phyllopods are embraced very differently formed Crustaceans 
of large and small size, living mostly in fresh water or salt marshes, and 
possessing in common little else than the leaf-like form of leg and a uniform 
developmental history. The segmentation of the body in higher forms 
(Branchiopoda) is very distinct, but in the water-fleas (Cladocera) it is usually 
quite incomplete. The number of body segments varies considerably 
among different genera. In the strongly segmented forms the body is 
elongated and protected in front by a flat or shield-shaped dorsal carapace 
(Apus), or it is naked (Branchipus). In the Cladocera and Estheriidae, which 
are enclosed in a bivalve shell, the body is laterally compressed, shortened, - 
and indistinctly segmented. The line of division between thorax and abdomen 
1 Literature: A. Recent Forms. 
Grube, E., Bemerkungen iiber die Phyllopoden, ete. (Wiegmaun’s Archiv fiir Naturgesch., XIX., 
XXXI.), 1853-65.—Claus, C., Papers on Branchipus, Apus, and Limulus in Abhandl. Gesellsch. 
Wissensch. Gottingen, XVIII., 1873 ; and Arbeit. Zool. Inst. Wien., VI., 1886.— Weismann, F. L. A., 
Zur Naturgeschichte der Daphniden (Zeitschr. Wissensch. Zool., XXVII., XXXIII.), 1876-80. 
Lankester, E. R., Several papers on Limulus, Apus, ete., in Quart. Journ. Microse. Soc., XXI., 1881. 
—Packard, A. S., Monograph of the Phyllopod Crustacea of North America (12th Ann. Rept. U.S. 
Geogr. and Geol. Surv. Terr.), 1883.—Hansen, H. J., Phyllopoda and Cirripedia. Plankton Ex- 
pedition, 1895. 
B. Fossil Forms. 
Jones, T. R., On Fossil Estheriae and their Distribution (Quar. Journ. Geol. Soc., XIX.), 1865. 
-—-Monograph of the Fossil Estheriae (Palaeontogr. Soc.), 1862.—5th and 7th Repts. Comm. 
British Assoc. Ady. Sci. on Fossil Phyllopoda, 1887-89.—Geol. Mag. Sept. 1890, Feb. 1891, Dec. 
1893, July 1894.—Trans. Geol. Soc. Glasgow, IX., 1890.—Clarke, J. M., New Devonian Phyllopods 
(Amer. Journ. Sci., XXIII.), 1882.—Hall, J., and Clarke, J. M., Palaeontology of New York, VIL, 
p. 206, 1888.—Bernard, H. M., Fossil Apodidae (Nat. Sci., XI.), 1897.—Schuchert, C., On the 
fossil Phyllopod genera Dipeltis and Protocaris (Proe. U. 8. Nat. Mus. XIX.), 1897. 

