DE. T. DAVIDSON ON EECENT BEACHIOPODA. 15 



Shell somewhat subjientagoual or pear-shaped, broadest anteriorly, tapering posteriorly, 

 longer than wide, rounded laterally, slightly indented iu front. Dorsal valve moderately 

 and evenly convex, somewhat flattened along the middle. Ventral valve deeper than the 

 dorsal one ; beak slightly incurved and moderately produced, obliquely truncated by a 

 rather large circular foramen, separated from the obtusely angular hinge-line by a well- 

 defined triangular area and long, narrow, dcltidial plates ; beak -margins sharply defined. 

 Surface of valves marked with numerous, wavy, fine, radiating riblets, widely separated 

 and crossed at intervals by concentric lines of growth. Colour ochreous white, csecal 

 tubuli minute and close-set. Loop small and simple. Length 1 inch 1 line, breadth 

 1 inch, depth 7 lines. 



Mab. OQ the coast of Portugal, in 500-600 fathoms ; in the Bay of Biscay. 



Ohs. The only complete specimen of this shell that I have seen is the one described, 

 which I figured for Dr. Jeffreys. It was given to me by Mr. Saville W. Kent, who had 

 dredged it during his cruise in Mr. Hall's yacht ' Noma ' off the Setubal coast, near the 

 Tagus in 1870. Since then I have been informed by Dr. Jeffreys that young examples 

 were obtained during the dredgings of the French shij) ' Travailleur ' in the Bay of 

 Biscay. It seems to be a good and well-marked species. 



8. LiOTHYRis Wyvillii, Davidsou. (Plate II. figs. 8-14.) 



Terebratula Wyvilli, Davidson, Proc. Roy. Soc. vol. xxvii. p. 436, 1878, and T. wyvilUi, Report on 

 the Brachiopoda, Voyage of H.M.S. 'Challenger/ Zoology, vol. i. p. 27, pi. ii. figs. 7, 8, 1880. 



Shell somewhat subpentagonal, variable in shape, about as broad as long, sometimes 

 almost square, with rounded angles, with a concave sinus on the dorsal valve and corre- 

 sponding fold in the ventral one. Shell very thin and exceedingly brittle, almost 

 transparent, smooth, glassy, light-yellowish white. Length 7, breadth 9, depth 4| 

 lines. Valves in the young slightly and evenly convex ; dorsal valve moderately convex, 

 with a depression of greater or less depth commencing close to the umbo, and gradually 

 widening and deepening as it nears the front, front line wide, straight, or presenting an 

 inward curve. Ventral valve deeper and more convex than the opposite one, with a wide 

 median coiixex elevation or fold commencing near the beak, and one extending to the 

 front. Beak very small, slightly incurved, truncated by a small, generally incomplete, 

 circular foramen, laterally margined by dcltidial plates. Surface of valves marked at 

 intervals by concentric lines of growth ; shell-structure with minute, widely separated 

 perforations or canals. In the interior of the dorsal valve the loop is short and simple ; 

 the adductor and other muscular impressions are small and delicate. The labial appen- 

 dages extend to two thirds of the length of the shell. In the interior of the ventral valve 

 the muscular impressions are small, and occiipy a limited area close to the beak. 



Sab. This remarkable and very interesting species appears to abound over a wide 

 geographical area, and at depths from 1035 to 2900 fathoms. 



It was dredged by the ' Challenger ' Expedition at six or seven different stations. In 

 South Australia, in lat. 42° 42' S., long. 134° 10' E., depth 2G00 fothoms : one example 

 was attached to a manganese nodule. In lat. 12° 8' S., long. 145 10' E., depth 1400 

 fathoms ; bottom-temperatm-c 1^-3 C. In lat. 33° 31' S., long. 74° 43' W., depth 2160 



