INTRODUCTION— CYPRIDINADiE. 



3 



The recent Polycope, characterized by its Hmbs as belonging to a different family to 

 that of the Cypridinadce, has a globose shell, with no notch, only an obsolete sinus ; 

 and among the Carboniferous fossils there are several to match this kind of carapace. 

 There are also some oblong forms, with oblique ends, which we name Bhomhina, and 

 believe to be related both to Ci/pridina and to some older genera known in the Silurian 

 rocks of Bohemia. 



To render the recognition and classification of the recent and fossil Cypridinad(B and 

 their allied groups more clear, we here indicate what is known of the existing forms, 

 especially as far as the features of the Carapace are concerned. 



The OsTRACODA are divided by G. O. Sars and G. S. Brady into four great 

 groups. 



I. PoDocoPA, comprising the Cypridm and the Cytherida. — " This is by far the 

 most extensive of the four sections, including all the freshwater and a vast majority of the 

 marine Ostracoda, and embracing all the forms classed by the earlier writers under the 

 two great genera Cypris and Cythere" (Brady, p. 355). The characters based on limbs 

 and other organs are enumerated at p. 355, &c., of Mr. G. S. Brady's memoir " On the 

 Recent British Ostracoda," in the 'Trans. Lin. Soc.,' vol. xxvi (1868). 



1. Cyprida. — "Valves mostly thin and smooth, more or less sinuate below'* 



(Brady, op. cit., p. 359). 



2. Cytlieridos. — " Shell mostly hard and compact, calcareous ; surface generally 



more or less rough and uneven, occasionally quite smooth " (Brady, op. cit., 

 p. 393). 



II. Myodocopa, embracing the Cypridinada and Conchoeciadce [and the Entomo- 

 concJddce^ — " This group comprises the forms of which the genus Cypridina is the type, 

 the characters indicating a higher organization and presenting well-marked differences, 

 which show an approach to the higher order Branchiopoda " (Brady, op. cit., 355). 



1. Cypridinadee. — "Shell mostly hard and compact in structure, smooth or punc- 

 tate, and sometimes beset with short hairs, notched at the antero-inferior 

 angle, so that when the valves are closed there remains still a large aperture 

 for the protrusion of the lower antennae " (Brady, op. cit., p. 462). 



1. Cypridina, Milne-Edwards., 



" Carapace produced in front into a more or less prominent beak, with a subjacent 

 hollow or notch facing the ventral margin " (Brady, ' Trans. Zool. Soc./ vol. v, p. 386). 



