22 DBEDGIKG EEP0KTS. 



also on the dorsal margin. Hinge line furnished in front with a 

 large tubercular hump, whence a well-defined rib passes down 

 the supero-anteal slope, and is continuous with the commence- 

 ment of the fringe of linguiform processes. Carapace seen from 

 below irregularly lozenge-shaped, having elevated longitudinal 

 riblets on each side of the junction of the valves, and the lingui- 

 form processes stretched out laterally as elegant wings, which 

 are widest behind the middle. End view in the form of an equi- 

 lateral triangle, the basal line of which is remarkably straight. 

 Length rather more than half a line. 



Cythereis Dunelmensis, n. sp. Pi. VII, figs. 1-4. 



Oblong. Dorsal and ventral margins straight but not parallel, 

 gradually inclining towards each other from the broad well 

 rounded anterior extremity to the rectangularly truncate poste- 

 rior end. Surface of valves excavated with cells, the interstices 

 between which stand out as a network. Carapace margined in 

 front by a row of beadlike spines ; posteal extremity of ventral 

 margin bearing four large, semi-erect, flattened, linguiform pro- 

 cesses ; other parts of the surface are also armed with small 

 spines, conspicuous among which is a tubercular spine at the 

 anterior extremity of the hinge line. Length half a line. 



The type specimen — for as yet I have only seen a single ex- 

 ample — was dredged 10-15 miles off Seaham in about 40 fathoms. 



[A description of the following species, though not procured 

 during the dredging expeditions, is added here, as it will com- 

 plete the list of new Cytheres, which have been met with on 

 the north eastern coast of England. 



Cythere celMosa, n. sp. PI. V, figs. 17-20 ; and PL VI, fig. 17. 



Nearly semicircular, but having one end of the semicircle 

 replaced by an angle ; highest in the middle ; length to breadth 

 as scarcely two to one ; compressed. Ventral margin straight ; 

 dorsal margin strongly arched, the arch being continued ante- 

 riorly until it meets the straight ventral margin, which scarcely 

 rises at all towards it ; posterior extremity with a produced 

 central angle, the upper and lower sides of which are unusually 

 straight and equally divergent. Carapace having the valves 



