DK. T. DAVIDSON ON EECENT BEACHIOPODA. 87 



extfint by tlie umbo of the dorsal valve and by two very small rudimentary deltidial 

 plates ; beak-ridges sharply defined, leaving between them and the hinge-line a small 

 flattened space. Hinge-line obtusely angular. Surface of valves smooth, marked with 

 strong concentric lines of groA\th ; shell-punctures rather large; and soin(>what widely 

 interspaced. In the interior of the dorsal valve the cardinal process is small, the hinge- 

 plates are disunited and form two concave projections, on each side of w^hich deep 

 dental sockets are situated. The principal lamella; of the loop are attached to the 

 bases of the hinge-plate, and these by a curve meet a slightly raised mesial septum, to 

 which they lioconie again attached ; at a short distance from this second attachment the 

 lamellae become reflected in a very remarkable and unusual manner. The large paired 

 adductor muscular impressions are situated at the bottom of the valve, and at some 

 distance from the mesial septum or ridge. In the ventral valve the curved articulating 

 teeth arc large and powerful. Colour ashen or yellowish grey. Length of a large 

 specimen 11 lines by 10 in breadth and 6 in depth. 



Hab. Western Aleutians from Atka Island westward ; Atka, Amchitka, Attn (Dall) ; 

 Ocbotsk Sea (Middendorff ) ; Japan seas (Capt. St. John). From low water to 45 fathoms ; 

 abundant in 10 fathoms. 



Obs. This is a very good and well-characterized species, well but not completely fio-ured 

 by Middendorff in 1819. The shell was subsequently al)undantly collected by Mr. Dall 

 and Capt. St. John. The Japanese examples are a good deal smaller than those figured 

 by the Eussian author, as well as those dredged by Dall at Atka Island, in the Aleutian 

 channel. Their interior is exceedingly remarkable, and differs in detail in many respects 

 from that occurring in the larger number of species of the genus, first in the shape of the 

 loop, and secondly in the position and dimensions of the adductor muscular impressions, 

 which are very powerful. These characters and differences will become at once apparent 

 by a glance at the figures, which I have drawn with all possible care and accuracy. The 

 shell is thick and presents a coarse appearance. 



44<. Teuebratella cruenta, Dillwyn, sp. (Plate XIV. figs. 1-8.) 



Anomiu saiif/iiinca, Solander, MS. Portland Cabinet; Leverian Cat. sec. part 15. 



Tert'brutuhi saiirjiiinea, Leach, Zool. Misc. p. 7Q>, tab. xxxiii. 1814 (not Chemnitz). 



? TerebratuJa sanyuinea, Lamarck, An. sans Vert. voL vi. p. 247, 1819 (not Chemnitz?). 



Terebratula cruenta, Dillwyn, Descrip. Cat. Recent Shells, vol. ii. p. 295, 1817. 



Terebratula sanffuinea, E. Donovan, Naturalist's Repository, vol. i. pi. 34, 1823. 



Terebratula Zelaiidica, Deshayes, Revue Zoologique par la Soc. Cuvierienne, p. 359, 1839, and Mag. 

 de Zoologie, Mollusques, pi. 42, 1841. 



Terebratula rubra, G. B. Sowerby, Thes. Conch, i. p. 345, pi. isviii. figs. 9-11, 1846 (not Pallas). 



Terebratula Zelandica, G. B. Sowerby, Thes. Conch, p. 361, pi. Ixxii. figs. 111-113, 1846. 



Lampas sarir/uineu.f, Calonne, Cat. Humphrey, MS. 



Terebratella Zelandica, Davidson, Ann. & Mag. Nat. Hist. 2nd ser. vo p. 367, 1852. 



Terebratella Evansii, Davidson, Proc. Zool. Soc. 1852, p. 77, pi. xiv. figs. 7-9. 



Terebratella cruenta, Woodward and Gray, Cat. of Brachiopoda in the Brit. ^lus. p. 89, 1853. 



Terebratella Zelandica, E. Suess, Ueber die Wohnsitze der Brachiopodcn, Sitzungsb. k. Akad. der 

 Wissensch. AVien, Bd. xxxvii.p. 207, 1859. 



