REPORT ON THE BRACHIOPODA. 47 



half the length of the valve to the front. Ventral valve deeper than the dorsal one, longitu- 

 dinally keeled. Beak short ; foramen rather large, completed by a narrow deltidium ; 

 beak-ridges well defined, leaving a flattened space or false area between them and the long- 

 obtuse angular hinge-line. Margin of valves strongly flexuous. Surface of both valves 

 ornamented with numerous radiating diverging ribs curving to the lateral margin, straight 

 along the middle, with shorter ribs interpolated between where the space widens to receive 

 them. In the dorsal valve the loop is doubly attached. Mesial septum large, and 

 abruptly elevated at its anterior extremity, extending from under the hinge-plate to 

 about two-thirds of the length of the valve. The principal branches of the loop are first 

 attached to the base of the hinge-plate ; again, at about two-thirds of their length, become 

 very much widened in the shape of horizontal expansions, which become fixed to the 

 middle of the top of the septum, the principal branches then continue to extend for a 

 short distance before becoming reflected and form the loop. Length 22, width 21, depth 

 5 mm. 



When quite young, and up to about 8 mm. in length, the shell is quite smooth, 

 the ribs afterwards commence to appear as the shell acquires age and size. 



Habitat. — About twelve or thirteen specimens of this species were dredged by the 

 Challenger Expedition in the Gulf of Patagonia, on December 28, 1875, at Station 

 312, in lat. 42° 43' S., long. 82° 11' W., or near Cape Horn, and not far from Falk- 

 land Islands, in 1450 fathoms. Bottom temperature, 1°'5 C. Sea bottom, globigerina 

 ooze. Six specimens were also dredged by the Challenger Expedition at Station 315, 

 January 26, 27, 28, 1876, in lat. 51° 40' S., long. 57° 50' W., Port Stanley, at a depth 

 of 5 to 1 2 fathoms. Sea bottom, sand and gravel. Specimens in the Smithsonian Cabinet 

 are labelled, " Orange Harbour, Patagonia." Captain P. P. King, R.N., the first discoverer 

 of the species, states — " This shell was dredged in the Bay of Port Famine, attached to 

 stones : it is a common shell in the Straits." 



Magasella incerta, Dav. (PL IV. fig. 6, a, h). 



Shell elongated, pear-shaped, broadest anteriorly, tapering posteriorly, very slightly 

 and evenly convex, somewhat flattened, without fold or sinus, smooth, nearly white. 

 Beak in ventral valve pointed, nearly straight, with a large incomplete foramen extending 

 from under the extremity of the beak to the hinge-line, and margined partly by the umbo 

 of the dorsal valve, and by small lateral plates. In the interior of the dorsal valve a short 

 elevated vertical mesial septum almost reaches to the bottom and middle of the opposite 

 valve ; it extends along the middle portion of the bottom of the dorsal valve to about 

 half the length of the shell ; to its sides and to the base of the hinge-plate are attached 

 the principal stems of the loop, the reflected portion l^eing small. Length 5, breadth 4, 

 depth Ih mm. 



Habitat. — Some twelve examples of this small shell were dredged by the Challenger 



