A Synopsis of the Recent British Ostracoda. 129 



Family — Polycopimi. 



Polycope, G. 0. Sars. — The principal characters of this 

 genus are those of the family to which it belongs, and of which 

 it is the only member. 



P. orbicularis, Sars. ; dentata, Brady. — The first-named 

 species is probably not very uncommon, but owing to its small 

 size — g-Vth. of an inch — is very likely to be often overlooked. 

 It has occurred in Connemara, Shetland, and the West of 

 Scotland. The shell is almost spherical, and often beautifully 

 punctate and marked out into polygonal areolae. Of the second 

 species only one example has yet been found ; this occurred to 

 Mr. Norman in the same gathering as that which yielded the 

 Conchoecia. According to the investigations of G. 0. Sars. 

 these animals are wonderfully active in the water, having no 

 less than ten limbs adapted for swimming. 



Family — C ytheeelltd.ze . 



Cytherella, Bosquet. — The anatomical structure has been 

 noticed in the description of the family. The shell is very thick 

 and dense in structure, the lateral outline mostly elliptical, and 

 the hinge formed by a simple grooving of the edge of one valve 

 into which the margin of the opposite valve is received. The 

 " lucid " spots* are arranged in a curved pinnate series. 



G. Scotica, Brady ; Icevis, Brady. — Both species are very 

 rare, and hitherto have been found only amongst the Hebrides. 

 The former is closely allied to a Norwegian species desci-ibed 

 by Sars — C. abyssorum. Several fossil species have been 

 described by various authors ; the great thickness and dura- 

 bility of the shell may perhaps account for this. 



Explanation op Plate I. 



Pig. 1. — Illustrating the anatomy of the female of the 

 genus Gypris : a, eye ; b, upper antenna ; c, lower antenna ; 

 d, mandible proper ; e, its branchial appendage ; /, its palp ; 

 g, first maxilla ; h, its branchial plate ; i, second maxilla, with 

 branchial appendage ; j, first foot ; h, second foot ; I, abdomen ; 

 m, post-abdominal ramus; n, alimentary canal; o, ovary. 



Pig. 2 illustrates the anatomy of the genus Gythere : the 

 letters used refer to the same organs as in Cypris, except those 



* These, though existing in all Ostracoda, have not, for the sake of brevity, 

 been previously noticed, though they sometimes afford good generic characters. 

 They are, iu fact, thin, depressed portions of the shell which afford attachment to 

 the muscular bands by which the animal is attached, and by which it is enabled 

 to close the valves firmly. 



VOL. XII. — NO. II. K 



