REPORT ON THE BEACHIOPODA. 49 



that the shell occurred off Port Jackson Heads, South Australia, and the Challenger 

 Expedition dredged four separate valves on April 17, 1874, off Port Jackson, in 2 to 10 

 fathoms. 



I regret that as my plates were finished prior to the discovery of this species among 

 the Challenger shells, that it could not be figured, but good illustrations of it have already 

 been given by both myself and Mr Lovell Reeve. 



It is possible that the so-termed Bouchardia ('?) fibula of Reeve may be only a large 

 example of M. cumingi, and belong to the same sub-genus. It is likewise said to have 

 been dredged alive somewhere ofi" South Australia, and not very far from where M. 

 cumingi is known to occur. 



Megerlia, King. 



Megerlia ("?) incerta, n. sp. (PL XL figs. 17, 18). 



Shell semicircular, small, somewhat broader than long. Hinge-line long and straight, 

 rather exceeding two-thirds of the breadth of the shell, with obtuse cardinal angles, semi- 

 transparent, whitish. Dorsal valve very slightly convex, most so at the umbo; ventral 

 valve a little deeper and more convex than the opposite one, slightly longitudinally 

 depressed along the middle. Beak small and truncated by an incomplete circular foramen, 

 laterally margined by small deltidial plates ; beak-margin very sharply defined, leaving 

 between them and the hinge-line a sharply-defined narrow area. Surface of both valves 

 marked by numerous rounded radiating ribs with concave interspaces, some bifurcating 

 near the front, or increasing in number by the interpolation of shorter ribs between 

 the longer ones. Surface of valves crossed at irregular intervals with concentric 

 lines of growth. Shell perforated by minute canals. Length 8, breadth 9, depth 

 4 mm. 



Habitat. — One young specimen attached to Limoj^sis aurita {?), Brocchi, and two or 

 three more aged examples were dredged by the Challenger Expedition, August 25, 1873, 

 in lat. 1° 47' N. long 24° 26' W., between Sierra Leone (Africa) and Fernando de Noronha 

 (South America) south of Cape Verde Islands, in 1850 fathoms, associated with Discina 

 atlantica. 



Observations. — I am uncertain with respect to the genus to which this small 

 Brachiopod should be referred, as I am unacquainted with the shape and character of its 

 loop. I did not like to run the risk of opening the shell or separating its valves, but the 

 strong general resemblance it bears to Megerlia truncata induces me to provisionally 

 leave it in that section of the Terebratulidse. The long straight hinge-line and sharply- 

 defined area are well exposed in three of the specimens. When young the ribs were few 

 in number, and the interspaces between them wide, the ribs becoming more numerous 

 and close as the sheU acquires age and growi:.li. 



(ZOOL. CHALL. EXP. PART I. — 1880.) A 7 



