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



outline, as Been from above, is oblong ovate or hastate, the junction of the hinge-margins 

 marked behind the middle by a deep, sharply denned sulcus. Ventral surface sulcate 

 alon- the whole length of the contact-margins, which are bordered by a broad, well- 

 defined, smooth band. End view ovate. The surface of the shell is marked with oblong 

 punctures, which are arranged chiefly in longitudinal rows, but in curved lines round the 

 anterioi border. The valves, in typical specimens, are swollen behind, forming an abrupt 

 alar elevation, from which a Longitudinal rib runs directly forwards, and two others 

 in oblique direction towards the upper and lower margins of the valve; the left valve 



considerably smaller than the right. Animal unknown. 



Lemrth ■£? in. 



- 



-> 111 33 



llab. In deep water, rare. Coasts of Northumberland and Durham, 25-46 fathoms (G. S. B.); Ormeshead 



(Mr. D. Robertson) ; Shetland (Rev. A. M. Norman) 



Minch (M> 



W> 



The specimen represented in figs. 19-22 is the form originally described by Dr. Baird 

 under the specific name qiiadridentata ; that shown in fig. 25 is a very similar form, 

 while fig. 23 differs only in being less angular and the surface-markings fainter. The 

 specimens from which figs. 26-30 were drawn appear to be merely a variety, or perhaps 

 the adult or the female of the same species. The peculiar characters of the ventral and 

 dor- J surfaces, as well as the elongated punctation, are distinctly retained. The species 

 is a rare one, and I have had no opportunity of thoroughly examining the animal. 



26. Cytuere emaciata, Brady. (Plate XXXI. figs. 31-37.) 



emaciata 



Atlantic type. Distribution : Recent — Great Britain and Ireland. Fossil — Raised beaches, Scotland. 



Carapace, as seen from the side, compressed, quadrangular, higher in front than 

 behind ; length equal to more than twice the height. Anterior extremity flattened or 

 but sligbtly rounded, often fringed with a row of eight or nine teeth. Posterior extremity 

 narrowed, excavated above, produced and toothed below. Dorsal and ventral margins 

 nearly straight. Outline, as seen from above, oblong, widest behind, nearly thrice as 

 long as broad ; the ventral keel produced behind into two broad fimbriated processes. 

 The contact -margins on the ventral surface are bordered by two flattened ridges, forming 

 a very broad keel, which projects considerably behind. End view oval, with rounded 

 lateral protuberances. Surface marked with large pits arranged longitudinally ; in small 



or young specimens the punctures are oblong, as in the preceding species ; along the 

 middle of the valve runs a conspicuous elevated rib, a less distinct ridge within the 

 ventral margin, and another smaller one in an oblique direction behind the antero-dorsal 

 angle. Right valve larger than the left. Animal unknown. 

 Length & to -3^ in., height ^5 to ^ in. 



Hab. In dec p water. Shetland {Rev. A. M. Norman) : Peterhead and (Vm«W 



(Ms 



J 



Hebrides (Mr. J. G. Jeffreys) ; Aberdeenshire coast (Mr. Dawson) j Northumberland and Durham 

 coasts, 35 fathoms, and Birterbuy Bay, 15 fathoms (G. S.B.); Devonshire coast, 60 fathoms (Mr- 

 Spence Bate) ; in shell-sand from Iloundstone (Dr. Alcock), Baltimore (Mr. E. C. Davison), and 

 Galway Bay (Prof. Rowney) . 



