DE. T. DAVIDSON OX EECENT BEACHIOPODA. 85 



Terebratella rubicunda, Davidson, Aim. & Mag. Nat. Hist. 2ud ser. vol. ix. p. 36", 1852 ; Woodward 



6 Gray, Catalogue of the Bracliiopoda in the British Museum, p. 89, 1853 {T. inconspicua is now 

 considered a synonym of T. rubicunda) ; E. Suess, Ueber die Wohnsitze der Brachiopoden, Sitzungsb. 

 k. Akad. der Wissensch. Wicii, p. 207, 1859 (T. inconspicua and a syn.) ; L. Reeve, Conch. Icon. pi. vii. 

 fig. 27, 18GI {T. inconspicua a syn.) ; Dall, Amer. Journ. Conch, vol. \\. p. 117, 1870, and Proc. Acad. 

 Nat. Sci. Philadelphia, 1873, p. 185. 



Magasella inconspicua, Dall, Amer. Journ. of Couch, vol. vii. p. dl , 1871, and Proc. Acad. Nat. Sci. 

 Philadelphia, 1873, p. 189. 



Terebratella rubicunda, F. W. Hutton, Marine Mollusca of New Zealand, p. 85, 1873. 



Shell somewhat orbicular or triangularly ovate, widest about tlie middle, acuminated 

 posteriorly ; dorsal valve moderately convex, channelled along the middle by a broad 

 concave sinus, commencing at the umbo and extending to the front, where it is produced 

 a little beyond the lateral curved margins of the valve. Marginal line flexuous on the 

 sides. Ventral valve deeper than the dorsal one, with a convex, well-defined, mesial fold 

 extending from the extremity of the beak to the front ; l)eak incurved and truncated by 

 a large circular foramen, lying close to the umbo or just separated from it by two rather 

 large deltidial plates that barely meet in the middle ; beak-ridges sharply defined. Surface 

 of valves either entirely smooth or more rarely with small short rounded ribs commencing 

 at a short distance from the lateral and frontal margins of the valves ; surface of valves 

 crossed by concentric strongly marked lines of growth. In the interior of the dorsal 

 valve the hinge-plate is well defined, with a cardinal process at its posterior extremity. 

 A mesial septum of small elevation proceeds from the base of the hinge-plate to about 

 one half the length of the valve. Loop doubly attached, first to the base of the hinge- 

 plate, and then by a transverse lamella proceeding from about the middle of the 

 length of the principal lamella to the anterior extremity of the septum, when, after 

 again extending a little further, the lamell.Te become reflected and united. Colour 

 pale or deep red, sometimes colourless. Length 1 inch 1 line, breadth 1 inch, depth 



7 lines. 



Sab. Fauveau and Cook's Straits, New Zealand ; Dusky Bay (Hutton). 



Ohs. Terebratella rubicunda is an exceedingly abundant shell in the seas of New 

 Zealand. It varies much in shape and character from the young up to the adult condition, 

 and its loop passes through several modifications during the progress of growth. 

 The youngest individual I have been able to examine measured three lines in length ; at 

 this stage and for some time after its septum is remarkable in shape and of considerable 

 elevation as in Ilagasella, but low at its origin under the hinge-plate. It soon assumes an 

 upward concave curve, to be followed by another still more oblique ; where it attains 

 its highest elevation, a flattened plane occurs and then gradually thins out by an abrupt 

 inward curve, until it reaches nearly to the bottom of the valve, the anterior half of 

 the septum presenting the form of a wide, elevated, flattened plate. In the young 

 stage under description the principal laminae or stems of the loop, after being attached 

 to the hinge-plate, form a curve and become fixed by their anterior edges to the 

 lateral sides of the septum ; a little higher up, and attached to the edge of the septxim, 

 are two wide, curved, disunited anchor-shaped lamellije. To this immature condition 

 I gave in 1850 the name Waltonia Valenciennesii, which must be expunged. To a 



12* 



