642 ARTHROPODA SUB-KINGDOM VII 
Order 2. CLADOCEHRA. Milne-Edwards. 
Phyllopods with bivalve shell which partially or entirely encloses the body ; antennae 
large, forming swimming organs ; four pairs of leaf-like thoracic feet. 
These have not yet been recognised with certainty in the fossil state. Possibly, 
however, Lynceites ornatus, Goldenberg, from the Carboniferous, belongs here. 
Super-Order 2. COPEPODA. Latreille. 
Body elongate, usually distinctly segmented, the anterior somites being fused, the 
posterior thoracic ones free. Both pairs of antennae well developed ; four or five pairs 
of biramous thoracic feet. Abdomen short or long, without appendages except for a 
long caudal pair. 
The Copepoda are without representatives in the fossil state. 
Super-Order 3. OSTRACODA. Latreille.' 
Small, indistinctly segmented Crustacea completely enclosed in a horny or calcareous 
bivalve shell. Only seven pairs of appendages present—two of antennae, one of 
mandibles, two of mazillae, and two pairs of thoracic feet. Abdomen short and 
rudimentary. 
As a rule only the bivalve shell of the Ostracoda is found fossil, and since 
the classification is based principally upon characters presented by the 
appendages, the relations of recent to fossil forms cannot be made out with 
certainty, especially as the form and ornamentation of the shell are largely 
independent of the internal organisation. 
The valves are closed by a sub-central adductor muscle, the attachment of 
which is marked on their inner sides by a tubercle, pit, or a number of small 
spots. The shell is compact in structure, commonly from 1 mm. to 4 mm. in 
length, although sometimes exceeding 20 mm. The outer surface may be 
1 Literature : 
Bosquet, J., Description des Entomostracés fossiles de la craie de Maestricht (Mém. Soe. Roy. 
Sci. Liége, IV.), 1847.—Description des Entomostracés fossiles des terrains tertiares de la France et 
de la Belgique (Mém. Couronn. Acad. Roy. Belg., XXIV.), 1850.—Monographie des Crustacés 
fossiles du terrain crétacé du Duche de Limburg (Mém. Commiss. Carte géol. Néerlande). Haarlem, 
1854.—Reuss, A. H., Die fossilen Entomostracen des dsterreichen Tertiaérbeckens (Haid. naturw. 
Abhandl., III. Pt. 1), 1850.—Die Foraminiferen und Entomostracen des Kreidemergels von Lemberg 
(ibid. IV., Pt. 1), 1851.—Jones, T. R., A Monograph of the Entomostraca of the Cretaceous Forma- 
tion of England (Palaeont. Soc.), 1849.—J/dem, and Hinde, G. J., A Supplemental Monograph of 
the Cretaceous Entomostraca of England and Ireland (idid.), 1890.—/Jones, T. R., A Monograph of 
the Tertiary Entomostraca of England (ibid.), 1857.—Jdem, and Sherborn, C. D., A Supplemental 
Monograph of the Tertiary Entomostraca of England (ibid.), 1889.—Jones, T. R., and Kirkby, J. W., 
Notes on Palaeozoic bivalved Entomostraca, Nos. 1-32 (Ann. Mag. Nat. Hist.), 1855-95.—Zgger. O., 
Die Ostracoden der Miociinschichten bei Ortenburg (Neues Jahrb. p. 403), 1858.—Speyer, O. W. C., 
Die fossilen Ostracoden aus den Casseler Tertiiirbildungen (Cassel Jahresber., vol. XIII.), 1863.— 
Brady, G. S., Crosskey, H. W., and Robertson, D., A Monograph of the Post-Tertiary Entomostraca 
of Scotland (Palaeont. Soc.), 1874.—Jones, T. R., Kirkby, J. W., and Brady, G. S., A Monograph 
of the British Fossil bivalved Entomostraca from the Carboniferous Formations (ibid.), 1874, 1884. 
—Jones, T. A., and Holl, H. B., Notes on Palaeozoic bivalved Entomostraca (Ann. Mag. Nat. Hist. 
[4], III.), 1869.—Brady, G. S., and Norman, A. M., A Monograph of the marine and fresh-water 
Ostracoda of the North Atlantic, ete. (Sci. Trans. Roy. Dublin Soc., [V., V.), 1889-96.—Lienenklaus, 
E., Monographie der Ostracoden des nordwestdeutshen Tertiiirs (Zeitschr. deutsch. geol. Ges., XLVI.), 
1894.—Jones, T. R., and Kirkby, J. W., On Carboniferous Ostracoda from Ireland (Sci. Trans. Roy. 
Dublin Soc., VI.), 1896.—Ulrich, #. O., The Lower Silurian Ostracoda of Minnesota (Geol. Minn., 
III. Pt. 2, Palaeont.), 1897.—Sherborn, C. D., The literature of fossil Ostracods (Nat. Sci. X.), 1897. 
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