RECENT BRITISH OSTRACODA. 



419 



Hab. In depths of from 2 to 60 fathoms. Orkney [Mr. C. W. Peach) ; Hebrides and the Minchj 

 45-60 fathoms [Mr. J. G. Jeffreys) ; Tobermory at roots of Laminaria, Shetland, Isle of Skye 

 and Lamlash Bay, and Dogger bank {Rev. A. M. Norman) ; Aberdeenshire coast {Mr, Dawson) ; 

 Oban, Cumbrae, Ormeshead, Bute, and Campbeltown {Mr. D. Robertson) ; Northumberland coast 

 (G. S. B.) ; in shell-sand from Roundstone {Dr. Alcock) ; off Lewis (N.B.), 59| fathoms {Admiralty 

 dredgings) *, 



33. Cytheee (?) ACEROSA, n. sp. (Plate XXXI. figs. 55-58.) 



Carapace, as seen from the side, reniform, liigliest in tlie middle, greatest height equal 

 to half the length. Anterior extremity flattened, subtruncate, obtusely angular at its 

 junction with the dorsal margin ; posterior rounded. Superior margin arched, highest in 

 the middle ; inferior deeply concave, nearly parallel with the dorsal margin. The an- 

 terior, posterior, and postero-ventral portions of the margin are excessively compressed 

 and laminar. Outline, as seen from above, oblong, hexagonal ; extremities suddenly 

 tapered, sharply acuminate, sides parallel; width equal to one-fourth of the length. 

 Surface smooth ; colour yellowish, opaque. Animal unknown. 



Length 4-3- in. 

 Hab. Plymouth {Rev. A. M. Norman). 



This remarkable species ought very probably to form the type of a distinct genus ; 

 but as I have had no opportunity of examining the animal, it seems best tempore to 

 place it in its present position. The only specimen extant is in the collection of the 

 Rev. A. M. Norman, and was obtained by the late Mr. Barlee from nets of trawlers at 

 Plymouth. 



Genus 2. Limnicytheee, Brady f. 



Shell irregularly tuberculate or spinous, rather thin, and horny in texture. Animal 

 like that of Cythere, except that the antennae are armed with short setae instead of 

 spines. Upper antennae five-jointed, slender, the last joint much elongated, the ante- 

 penultimate excessively short. Postabdomen terminating in two rather stout setae. 

 Inhabits fresh water. 



Of this genus I have not yet seen the males ; but the structure of the upper antenna, 

 together with the external characters of the carapace and the freshwater habitat, seems 

 to require that it should be placed in a distinct genus. I think it very probable that a 

 more minute examination than I have yet been able to make may reveal also other dif- 

 ferences than those here specified. 



1. LiMNiCYTHERE INOPINATA (Baird). (Plate XXIX. figs. 15-18, Plate XXXVIII. 



fig. 9, and Plate XXXIX. fig, 1.) 

 Cythere inopinata, Baird, Brit. Entom. p. 172, tab. xx. figs. 1, 1 a-e. 



Valves, as seen from the side, reniform, irregular, tuberculate, highest in the middle ; 

 greatest height equal to more than half the length. Anterior border rather narrower 

 than the posterior, rounded, and produced into a flattened encircling flange. Posterior 



* See Appendix. 



t Intellectual Observer, vol. xii. p. 121. 



3 L 2 



