REPORT ON THE BRACHIOPODA. 27 



Description of the Species dredged by the Challenger Expedition. 



Terebratula, Llhwyd. 



Terehratula ivi/viUii,Da,v. (PI. 11. figs. 7-9). 



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

 almost square, with a depression in the dorsal valve and fold in the ventral one. Shell 

 very thin, almost transparent, smooth, glassy, yellowish-white ; length and breadth 17 

 or 1 8 mm., depth 9 mm. Valves in the young shell slightly and evenly convex ; 

 dorsal valve moderately convex, with a wide or narrow concave depression of greater or 

 lesser 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 longitudinal 

 convex fold commencing near the beak and extending to the front. Beak very small, 

 slightly incurved, truncated by a small, generally incomplete, circular foramen, laterally 

 margined by deltidial 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 very small and delicate, the labial appendages extend to two-thirds 

 of the length of the shell. In the interior of the ventral valve the muscular impressions 

 are small, and occupy a limited area close to the beak. 



Habitat. — This very interesting species appears to abound over a wide geographical 

 range, and at depths varying from 1035 to 2900 fathoms. 



Station 160 (PL II. fig. 7, a, h, c), March 13, 1874, lat. 42° 42' S., long. 134° 

 10' E. Depth, 2600 fathoms. Bottom temperature, 0°-2 C. South Australia. One 

 example was attached to a manganese nodule. Sea bottom, red clay. 



Station 184, August 29, 1874, lat. 12° 8' S., long 145° 10' E. Depth, 1400 

 fathoms. Bottom temperature, 1°'8 C. Sea bottom, grey ooze. 



Station 299 (PL II. fig. 8), December 14, 1875, lat. 33° 31' S., long. 74° 43' W. 

 Depth, 2160 fathoms. Bottom temperature, l°'l C. Sea bottom, grey mud. Ofi' coast of 

 Chili or Valparaiso ; along with it was dredged Waldheimia ivyvillii and Discina atlantica. 



Station 302 (PL 11. fig. 9), December 28, 1875, lat. 42° 43' S., long 82° 11' W. 

 Depth, 1450 fathoms. Bottom temperature, 1° "5 C. Sea bottom, globigerina ooze. Off" 

 coast of Patagonia. 



Station 317. One small example from the net weights, not far from Falkland Islands. 

 February 8, 1876. Depth, 1035 fathoms. 



Station 244, June 28, 1875, lat. 35° 22' N., long. 169° 53' E. Depth, 2900 fathoms. 

 The greatest depth at which any Brachiopod was obtained by Challenger Expedition. 

 Bottom temperature, 1°*2 C. Sea bottom, red clay. 



