382 CRUSTACEA ENTOMOSTRACA. 



Order 3. OSTRACODA.* 



Small, usually laterally compressed Entomostraca, with a bivalve 

 shell and usually with seven pairs of appendages, which serve as 

 antennae, jaws, creeping and swimming legs. There is a large 

 mandibular palp, and a short abdomen ending in a simple plate 

 or a caudal fork. 



16 

 '1.1 



FIG. 25B.Stenocijpris malcolmsonii (Brady). ( = Cypris cylindrica Baird). The right half of 

 the shell has been removed. 1 median eye ; 2 anterior antenna ; 3 posterior antenna ; 

 4 mandible ; 5 mandibular palp ; 6 first maxilla ; 7 second maxilla ; 8 and 9 thoracic 

 appendages; 10 caudal fork; 11 ovary; 12 advanced ova; 13 bundles of fibres of ad- 

 ductor muscle; 14 upper lip; 15 stomach; the caecal diverticulum of the left side is 

 seen in the fold of the shell below 11; 16 the leader points a little below the intestine. 

 (After G. O. Sars.) 



The body of these small Crustacea is unsegmented and is 

 completely enclosed in a bivalve shell, which gives the animal 

 a resemblance to a mussel. The surface of the shell may be 

 smooth, or variously sculptured, or beset with setae. In the 



* Besides Straus-Diirkheim, Fischer, Lilljeborg, Baird and others 

 compare W. Zenker, Monog. d. Ostracoden, Arch. /. Naturgesch., XX, 

 1854. G. O. Sars, Oversigt af Norges marine Ostracoder, Vid. Selsk. 

 ForTi. Christiania, 1865. C. Glaus, Beit. z. Kenntniss d. Ostracoden. Ent- 

 wicklungsgesch. v. Cypris, Marburg, 1868. ' Id. Die Halocypriden des 

 atlantischen Oceans und Mittelmeeres, Wien, 1891. Id. Beitr. z. Kenntniss 

 d. Siisswasserostracoden, I and II, Arb. Zool. Inst. Wien, 1892 and 1895. 

 G. S. Brady, A monograph of the recent British Ostracoda, Trans. Linn. 

 Soc., London, XXVI., 1868. Id. Ostracoda, Challenger Rep., 1, 1880. A. 

 Kaufmann, Beitr. z. Kenntniss d. Cytheriden, Receuil Zool. Suisse, iii, 

 1886. O. Nordqvist, Beitr. z. Kenntniss d. inneren mannlichen Gesch- 

 lechtsorgane d. Cypriden, Act. Soc. Sc. Fenn, xv, Helsingfors, 1885. 

 G. S. Brady and A. M. Norman, Monog. of the Marine and Fresh-water 

 Ostracoda of the N. Atlantic and of N.W. Europe. 1. Podocopa. Trans. 

 R. Dublin Soc. (2) vol. 4 (1889), p. 61. G. W. Miiller, Die Ostracoden d. 

 Golfes v. Neapel. (Naples Monograph Xo. 21), Berlin, 1894. Id. Deutsch- 

 lands Susswasserostracoden* Zoologica, 1900. 



