DR. T. DAVIDSON ON KECENT BRACHIOPODA. 171 



fold, scarc(;ly raised above the general convexity of the valve, occupies ihe anterior half 

 of the valve. Ventral valve rather less deep and convex than the opposite one, with a 

 broad well-defined mesial sinus, commencing at a short distance from the extremity of 

 the beak and extending to the front ; beak rather small, acute, and incurved ; foramen 

 incomplete, situated under its pointed extremity, laterally margined by narrow deltidial 

 plates ; surface of both valves ornamented Avith about forty to forty-six small, am^^ular, 

 radiating ri])s, closely intersected by equidistant, squamose, concentric I'idges of growth, 

 giving an imbricated appearance to the surface. Colour whitish, sometimes brownish, 

 especially at the beaks. Length 9 lines, breadth 10 lines, depth lines. 



Hah. Six examples were dredged by tlie ' Challenger ' Expedition south of Kerguelen 

 Island, associated with numerous specimens of JFaldheimia kerguelenensis ; at a depth 

 of 150 filth oms. 



Ohs. Nearly all the specimens of tlie typical forui from Faveaii Strait were of a blue- 

 black or brownish colour, while the six examples of the variety pyjcidata dredged by the 

 ' Challenger ' Expedition were of a light yellowish-white colour ; but as one showed at 

 the beaks the brown tint of the New-Zealand type, it is probable that some specimens of 

 the variety were also of a light brown colour. Tlie ribs in the latter are likewise more 

 numerous and smaller. These differences, no doubt, led the Rev. E,. Boog Watson to distin- 

 guish it as a distinct species under the MS. name o? pi/xidaia, from Trvz,iov, as he thought 

 it like a box in form. After careful study and comparison with an extensive series of 

 New-Zealand types, I am led to the conclusion that Bhynchonella pyxklata is merely a 

 local variety of R. nigricans. A species of Bhynchonella recently found by the Rev. J. E. 

 Tenison Woods in the Tertiary rocks of Table Cape, Tasmania, seems absolutely undistin- 

 o-uishablc. It has received the MS. name lihynchonella ccclata from Prof. M'Coy, and 

 was described under that name by the Rev. Tenisou Woods in a paper on the Tertiary 

 deposits of Australia, published in the ' Proceedings of the Royal Society of New South 

 Wales' in 1877. 



98. Rhynchonella. coknea, P. Fischer, MS. (Plate XXV. hgs. 2-4.) 

 ? Rhynchonella sicula, Gwyn JefEreys, Proc. Zool. Soc. 18~8, p. 113, pi. x\iii. figs. 5, G. 

 Shell thin, ovately triangular, broadest anteriorly, tapering posteriorly, rounded 

 laterally, very slightly so in front. Dorsal valve moderately convex, without either fold 

 or sinus, slightly depressed along the middle. Ventral valve ratlier deeper and more 

 convex than the opposite one, and slightly depressed from the middle of the valve to the 

 front ; beak short, incurved, with a small circular incomplete foramen uiidcu- its angular 

 extremity, and laterally margined by narrow deltidial plates ; margins gently tiexaous, 

 and slightly curved in front. Surface of valves covered with numerous close-set very 

 fine longitudinally radiating striie, and crossed by a few fine concentric lines of growth ; 

 shell-structure fibrous. Colour pale brownish yellow. Valves articulating by means 

 of small teeth and sockets. In the interior of the dorsal valve the hinge-plate is 

 divided along the middle, with a mecUan groove along each of its parts, from which 

 extend two thin curved lamellse denticulated at their extremity; undi-r the hinge-plate 



SECOND SERIES. — ZOOLOGY, VOL. IV. 23 



