RECENT BRITISH OSTRACODA. 



>7 



almost obsolete in the adult, forming a mere transverse tumid elevation of the valve. 

 The anterior margin is broad, well rounded below, and more gradually curved abm. 

 where it terminates in a rounded elevation over the anterior hinge. The Posterior 

 margin is narrowed, and rather abruptly angular in the middle Ventral margin nearly 

 straight, or gently incurved in the middle: dorsal elevated over the anterior binge, 

 thence sloping in an undulating line to the posterior extremity. Seen from above th< 

 carapace is ovate, broadest behind, width somewhat less than the height; extremities 

 obtuse, outline very irregularly undulated; no eye-tubercle. End view in*, rularly qu - 

 urate, somewhat tapering above. Hinge-processes of the right valve strongly developed ; 

 of the left obsolete (fig. 29). Surface marked with large and dec]) pittings, often inter- 

 spersed with much smaller ones, and, in the intervals, bearing elevated papillae. Anterior 

 border mostly fringed with a series of from five to twenty, aud the posterior extremity 

 with about six teeth; but these are often entirely absent. Colour yellowish brown. 

 Limbs deep yellow. Shell of the male much elongated, length more than twice the 

 height, upper margin slightly concave behind the anterior hinge (iig. 30). Uppn 

 antennae six-jointed, last joint a little longer than the preceding. Drticating seta \ cry 

 slender. Claw of first foot pectinate on its inner margin. Second joint of last foot 

 rather longer than the united length of the two following joints, terminal claw very Long 



and slender. Male copulative organs produced into a much elongated and slender 

 process in front, the apical portion forming two prolongations, the anterior obtusely 



hooked, the posterior acuminate. 

 Length A in . 



O u " 2 5 



Minch, Shetland and Channel Islands {Mr. J. G. Jeffireg 



tan 



Bute, Campbeltown, and Cumbrae [Mr. J). Robertson); Dogger bank, Exmouth, Plymouth, Isle of 

 Skye, and Tobermory {Rev. A. M. Norman) ; Orkney {Mr. C. W. Peach) ; Northumberland and 



ham coasts, 20-46 



e coast {M. 

 from Ealtii 



The characters upon which I rely to distinguish this fine species me the central 

 tubercle, which is never, so far as I know, entirely wanting; the too posterior thereto 

 or, in old specimens, the transverse elevation resulting from their coal* once winch gxrea 

 to the dorsal view a somewhat cuneate outline ; and the absence mostly of Buy conspi- 

 cuous tubercle over the anterior hinge, and of any well-defined longitudinal sulcus on ft 

 dorsal aspect. But. even thus restricted, there is great variety in the ^ffcrcnt form, oi 



apace, as wiU be sufficiently seen by reference to the figures in Plate XXX 



is shown in 



mooth but prominently tubcrculated character of young specimens '* ™ 

 V 38-39, while the gradual disappearance of the tubcrc cs and-o— cou ; d £ 

 ■nent of the minor surface-markings may be traced upwards m «£«£*»*£ £ 



«nally, fig. 32 shows a still older form in ^^^SSSXi 

 Partially obliterated by calcareous deposit, as has been pieuoua 



°f other species. 



