THE OSTRACODA 791 



Baker, in 1753, is said to be the first author who sufficiently de- 

 scribed any of these small forms so that the description could be 

 recognized as referring to a Cypris. In the work " Employment 

 for the Microscope" an anonymous correspondent describes an 

 insect with a bivalve shell, somewhat resembling a fresh-water 

 mussel, and gives a figure of it lying on its back. 



Linnaeus, in his "Systema Naturae," in 1748, mentions a 

 species under the name "Monoculus concha pedata." For many 

 years the general term " Monoculus" was in use for all en- 

 tomostraca until finally, in 1776, 0. F. Miiller, in his "Zoologiae 

 Danicae Prodromus, " first established the genus Cypris, as well 

 as a number of other genera of the entomostraca. 



In 1894 G. W. Miiller published his masterly work on the Ostra- 

 coda of the Gulf of Naples. His descriptions and figures are most 

 carefully and accurately made, and in connection with his similar 

 work on the fresh- water Ostracoda of Germany, published in 1900, 

 may well form the best published basis for future work. He de- 

 scribes about 125 species from the Gulf of Naples and some 65 for 

 Germany. 



Structure. It is not uncommon for the extremities and ventral 

 edges of the shell of Cypris to exhibit a number of subparallel 

 canals (Fig. 1271) which radiate outwards, and are called "pore 

 canals." The same regions may be tuberculate, the right valve 

 alone with tubercles as in the subgenus Cyprinotus (Fig. 1270), or 

 the left valve alone similarly tuberculate as with the subgenus 

 Heterocypris. Various species of other groups may thus be simi- 

 larly marked. Occasionally the shell may show a series of longi- 

 tudinal markings, as Ilyodromus (Fig. 1259) or a network of 

 anastomosing and parallel lines, as Cypria exsculpta. 



Exclusive of the abdominal appendages, called the furca, there 

 are seven pairs of appendages in the Cyprididae. These may be 

 enumerated as follows: first antenna, second antenna, mandible, 

 first maxilla, second maxilla, first leg, and second leg, naming one 

 of each pair (Fig. 1244). 



The anterior lip or labrum (Fig. 1244) forms a prominence pro- 

 jecting between the bases of the second antennae and anteriorly 

 covering the oral orifice. The posterior lip or labium (Fig. 1 245) 



