A Synopsis of the Recent British Ostracoda. 119 



female armed with two long claws. Last pair of feet four- 

 jointed, flexuous, terminating in several long setse, the margin 

 of one of which (Fig. 5) is beautifully pectinated. Post- 

 abdominal rami (Fig. 6) well developed. Shell thin, higher in 

 front than behind, covered, more or less, with fine appressed 

 hairs. Marine. 



P. mytiloides (Norman) ; acupunctata, Brady ; trigonella, 

 G. 0. Sars ; angusta, Brady. — These animals, of which the 

 first-named is by far the most common, seem to delight in a 

 muddy bottom ; their movements are far from active, and they 

 have not much capacity for swimming. P. mytiloides often 

 occurs pretty plentifully in the mud of sheltered, quiet bays, 

 and I have found it very abundantly amongst the ooze from 

 oyster-barrels. 



Baiedia, M'Coy. — The anatomical structure of this genus is 

 as yet very imperfectly known, but is most probably nearly 

 similar to that of the following genus. It differs, however, in 

 having the post-abdominal rami very large and well developed. 

 The valves are very unequal in size, the left being much the 

 larger and overlapping the right both on the dorsal and ventral 

 surfaces ; outline subrhomboidal. 



B. inflata (Norman) ; acanthigera, Brady ; obtusaia, G. 0. 

 Sars ; complanata, Brady. — The first-named species is very 

 closely allied to B. subdeltoidea, a form first described from 

 fossil specimens, but having a very wide range at the present 

 day, extending over the Atlantic and Indian Oceans and into 

 the Mediterranean. In the British seas its place is taken by 

 B. inflata, which has not yet been observed in any other region. 

 I possess specimens of B. subdeltoidea dredged off Guernsey, 

 but these have every appearance of being fossilized. 



Maceocypeis, nov. gen. — Antennas short and robust, the 

 upper seven-jointed and shortly setiferous, the lower five- 

 jointed and armed with long apical claws. First pair of jaws 

 having an unusually small, subovate, branchial plate ; second 

 pair destitute of any branchial appendage ; palp, in the female, 

 large and subpediform, in the male, very robust and clawed. 

 First and second pairs of feet very different in structure, the 

 first pediform and strongly clawed, the second entirely covered 

 by the shell. Post-abdominal rami rudimentary. The male 

 possessing a long and narrow mucous gland. Shell elongated, 

 attenuated at the extremities, smooth and polished ; right 

 valve larger than the left and overlapping on the dorsal 

 margin. 



M. Minna (Baird). — This fine species is very rare in Britain, 

 having been found only off the coast of Shetland, but in the 

 Norwegian seas it appears to be more common. It is referred 

 by Sars to the genus Bairdia, that author not having seen any 



