DR. T. DAVIDSON ON EECEXT BRACHIOPODA. 123 



Obs. This pretty little species is nearly related to KraiisHina pimm, but is distinguish- 

 able from it by its more orbicular shape and crimson rays. The Kraussina capensis 

 (Gmelin) being a synonym of K. rubra, Pallas, I proposed in 1852 to alter its name 

 to K. Deshayesi. I regret not being able to agree with Mr. Ball's suggestion that the 

 name capensis can be retained for this form, as it is a synonym of another species 

 of the same genus. It is. moreover, well distinguished from Kraussina rubra. 



73. Kraussina pistjm, Valenciennes, apud Lamarck, sp. (Plate XXI. figs. 1-4..) 



Terebratula pisum, Valenciennes, apud Lam. Animaux sans Vert. vol. vi. p. 330, 1819. 



Ter ebr atula Natalensis, Kuster, Martini & Chemnitz, Conch. -Cab. vol. vii. p. 3G, pi. 2h. fio-s. 4-7 

 1843. 



Terebratula Alt/oensis, G. B. Sowerby, Proc. Zool. Soc. 1846, p. 95 ; and Thes. Conch, p. 302, 

 pi. Ixxi. figs. 91, 92, 184G. 



Terebratula Nataleiisis, Krauss, Sudafrikanischen Mollusken, p. 33, pl. ii. fig. 11, 1848. 



Terebratula piston, Davidson, Ann. & Mag. Nat. Hist. 2ud ser. vol. ix. p. 370, 1852. 



Kraussia pisum, H. & A. Adams, The Genera of Recent Mollusca, vol. ii. p. 579, pl. cxxxi. figs. 4«, A, 1858. 



Kraussina pisum, E. Suess, Ueber die Wohusitze der Brachiopoden, Sitzuugsb. k. Akad. der Wisseiisch. 

 Wien, Bd. xxxvii. p. 211, 1859. 



Terebratula [Kraussia) pisum, Lovell Reeve, Conch. Icon., Monogr. Tereb. pl. is. fig. 36, a, b, 1861. 



Kraussina pisum, Uall, Amer. Jom-n. of Couch, vol. vi. p. 140, 1870; Davidson, Report on the 

 Brachiopoda, Voyage of H.M.S. ' Challenger,' Zool. vol. i. p. 54, pl. iv. figs. 7, 8, 1880. 



Shell suborbicular or oval, often rather wider than long, light yellowish white. Dorsal 

 valve very slightly convex, with a groove-like central longitudinal depression extending 

 from the umbo to the front. Hinge-line nearly straight, and rather more than half as 

 long as the breadth of the shell. Ventral valve deeper than the dorsal one, longitudinally 

 keeled, beak slightly incurved, with a rather large incomplete foramen, and two small 

 lateral deltidial plates ; beak-ridges sharply defined, leaving a flattened area between 

 them and the hinge-line. Surface of valves covered with numerous small radiating ribs, 

 which increase in number at variable distances from the beak and umbo, owing to the 

 bifurcation of many of the ribs and the interpolation of shorter ones. Valves crossed 

 at variable intervals by fine concentric lines of growth. In the interior of the dorsal 

 valve the hinge-plate is narrowed, a very slightly raised mesial septum extending from 

 the middle of the hinge-plate to about half the length of the valve. From the anterior 

 extremity arise two short, deviating, flattened, and forked lamellge, expanded at their 

 extremities ; two eye-shaped depressions due to peduncular muscles He on each side of 

 the posterior extremity of the hinge-plate. The brachial a])pendages are small, and do 

 not occupy a space larger than about half the length of the valve ; central spiral lobe 

 very small. Length 8 lines, breadth 8 lines, depth 3 lines. 



Hab. This species was dredged by the ' Challenger ' Expedition off" the Cape of Good 

 Hope, at a depth of 150 fathoms. It has also been obtained near Natal, and by Sir E. 

 Belcher in the same localities. 



Obs. This species is well distinguished from Kraussina Lamarchiana by its numerous 

 delicate raised strife, but it is scarcely distinguishable from Kraussina Deshayesi, except 



second series. — ZOOLOGY, VOL. IV. 17 



