38 DR. T. DAVIDSON OX EECENT EEACHIOPODA. 



" Shell triangularly pear-shaped, orange flesh-colour, radiately obsoletely ridged, ridges 

 distant, with numerous bifurcated striae coming between them, beak obtusely produced, 

 foramen rather large, incomplete, deltidium obsolete ; loop short" (Reeve). Length 5, 

 breadth 4|, depth 2^ lines. 



Rab. Cape of Good Hope (dredged at a depth of 120 fathoms by Sir E. Belcher). 



Ohs. I have seen three examples only of this species (?), one of which was attaclied to a 

 specimen of Krauss'ma rubra. In the type ligured by E-eeve there is evidence of a 

 longitudinal depression along the middle of the dorsal valve, and in an authenticated 

 example in my possession the riblets seem somewhat fasciculated. 



Dall, at page 180 of his " Catalogue of the Recent Species of the Class Brachiopoda " 

 (Proc. Acad. Nat. Sci. Philadelphia, 1873), places T. abijssicola among his synonyms of 

 T. Jajionica ; but I fear I cannot concur with my friend in this identification. The Cape- 

 of-Good-Hope form is evidently more nearly related to T. caput-serpentls than to 

 T. jafonica. More specimens will have to be examined before a positive conclusion can 

 be arrived at with respect to its specific claims. 



22. Terebratulina ? incerta, Davidson, (Plate VI. figs. 23-25.) 



Megerlia (?) incerta, Davidson, Proc. Royal Sec. vol. xxvii. p. 438, 1878; and Report on the Brachio- 

 poda, Voyage of H.M.S. ' Challenger/ Zoology, vol. i. p. 49, 1880. 



Shell small, nearly circular, somewhat broader than long, widest towards the middle. 

 Hinge-line long, nearly straight or very obtusely angular, rather exceeding two thirds of 

 the breadth of the shell, with obtuse cardinal angles. Dorsal valve somewhat semicircular, 

 very slightly convex, most so at the umbo, lateral sides of the umbo auricular, no fold or 

 sinus. Ventral valve a little deeper or more convex than the opposite one, slightly longi- 

 tudinally depressed along the middle ; beak short and truncated by an incomplete circular 

 foramen margined by the umbo of the dorsal valve and by two lateral deltidial plates ; 

 beak-margins sharply defined, leaving between them and the hinge-line a narrow area. 

 Surface of both valves marked by numerous fine rounded radiating riblets with concave 

 interspaces, some of the ribs bifurcating near the front, other shorter ones intervening 

 between the longer ones at variable distances from the beaks. Valves crossed by 

 numerous irregular concentric lines of growth. Shell perforated by minute canals. 

 Colour yellowish white. In the interior of the dorsal valve the cardinal process is long 

 and narrow ; the loop short and simple. Lengtli 5, breadth 5^, depth 2| lines. 



Hab. One young example attached to L'mioims aurifa {?), Brocchi, and two or three 

 more were dredged by the ' Challenger ' Expedition between Sierra Leone (Africa) 

 and Eernando de Noronha (South Atlantic) in 1850 fathoms, associated witli Disciniscu 

 atlantica. 



Obs. In 1880, when describing this shell for my ' Challenger ' lleport, I felt very 

 uncertain with respect to the genus to which it should be referred, especially as I was 

 unacquainted with the sliape and character of its looj:), and did itot like to run the risk of 

 opening the shell and separating its valves. Since then a number of specimens having 

 been obtained during the ' Blake ' Expedition, Mr. Dall was able to examine the loop, 

 which he found to be simple and short, as in Terebmtida or Terebratulina ; the lateral 



