398 MR. G. S. BRADY'S MONOGRAPH OF 



different specimens. Specimens from deep water are often much incrusted and porcel- 

 laneous, the surface-sculpture almost obliterated (see fig. 28). Colour brown, or dull 

 uhitr. Colour of the animal deep brown. Antennae short and stout, the fourth joint 

 ver short, the last much elongated and slender, nearly twice the length of the pre- 



g. Second joint of the mandibular palp broad at the apex, the last joint armed 

 with three short spines. Last pair of feet fully twice as long as the first, the second 

 joint very long, the last joint bearing at the apex four short and sharp spines. Copu- 

 la tive organs of the male dilated at the extremity, and produced into long tapering 

 processes, one of which is much more slender than the other. Abdominal lobes feebly 

 developed and bearing a short seta. 



Length ^ in., height ^$ in. 



littoral 



Shetland, Stornoway, Skye, Lamlash Bay, Tenby, 

 m and Channel Islands (Rev. A. M. Norman) : 



Arr 



Orkney Mr. C. W.Peach); Aberdeenshire coast (Mr. Dawson) ; Oban, Cumbrae, Campbeltown, 

 Macduff", Peterhead, und Ormeshcad, dredged (Mr. D. Robertson) ; dredged amongst the Hebrides 

 and Channel Islands (Mr. J. G. Jeffreys) j Devonshire coast, 60 fathoms (Mr. Spence Bate) ; Norfolk 

 coast (Mr. D. 0. Drewett) ; in shell-sand from the Mumbles (South Wales) , the Kibble, Preston 

 Tans, Stranraer, Margate, Baltimore, Donegal Bay, and Roundstone; Northumberland and Durham 

 coa s, 25-46 fathoms, and Birterbuy Bay, 15 fathoms (G. S. B.). 



i "it there pellucida, though exceedingly variable in habitat, surface-sculpture, and in the 



proport ions of the carapace, is easily distinguished by the peculiar dorsal angulation of 



the posterior border and by its one or more deep transverse sulci. Old specimens, how- 



ver, are not always recognizable with facilitv, the surface-markings becoming very 



vague, and the contours of the shell less characteristic. The following species approaches 

 very closely to C. pellucida, but is never met with except in brackish or subbrackish 

 situations ; and, in addition to this peculiarity of habitat, its shell-structure affords 

 characters which, on close examination, will not fail to distinguish it. 



4. Cytiii: i; e casta nea, G. 0. Sars. (Plate XXVIII. fig. 27, and Plate XXXVIII. fig. 6.) 



Cythere castanca, G. O. Sars, Oversigt af Norges marine Ostracoder, p. 32. 



Brituh type. Distribution : Recent— Great Britain, Norway. Fossil— Glacial, Scotland. 



Carapace of the fern ale, as seen from the side, subreniform. rather higher in front than 



behind, greatest height in front of the middle, equal to half the length. Anterior ex- 

 tremity well rounded, posterior rounded off below, angular above at its junction with the 

 dorsal margin ; superior margin slightly arcuate and sloping backwards from the ante- 

 rior third, where it is highest ; inferior distinctly sinuated in the middle, curving upwards 

 behind. Scon from above, the outline is ovate, widest in the middle, in front of which 

 it i^ distinctly constricted, pointed in front, rounded behind, greatest width considerably 



less than the height. The shell of the male, seen laterally, is much more tapered 



behind; the supero-posteal angle much pronounced, the infero-posteal thoroughly 

 rounded off; dorsal margin quite straight and rather steeply sloping backwards. Surface 

 of the valves thickly covered with small rounded depressed puncta, and marked with 



