REPORT ON THE BRACHIOPODA. 45 



yellow, sometimes slightly yellowish-red, smooth or ribbed. Dorsal valve, with a 

 mesial depression or sinus commencing generally at about half the length of the valve, 

 and extending to the front. Ventral valve rather deej^er than the dorsal one, with a 

 mesial fold corresponding to the sinus in the opposite valve. Beak produced, slightly 

 incurved and truncated by a rather large circular foramen, more or less separated from 

 the hinge-line by a deltidium in two pieces ; beak-ridges sharply defined, leaving a 

 flattened space between them and the hinge-line. In the interior of the dorsal valve the 

 loop is long and doubly attached, first to the hinge-plate, again by horizontal laminae, 

 given ofi" by the principal branches of the loop, to a slightly elevated mesial septum. 

 Length 25, width 26, depth 11 mm. 



Habitat. — Three examples were dredged by the Challenger, ofi" Royal Sound, Ker- 

 guelen, on the 17th January 1874, lat. 49° 40' S., long. 70° 20' E. Depth, from 20 to 

 30 fathoms. It is a very common species near the coast of Chili and southward to the 

 Straits of Magellan, in depths of from 25 to 90 fathoms. Mr Cuming got it near 

 Valparaiso. A. D'Orbigny states, in his Voyage dans I'Amerique Meridionale, that he 

 obtained it also at Coquimbo at rather great depths. Some specimens have attained to 

 double the size of the Challenger specimens above recorded. 



Observations. — This species varies considerably from the presence or absence of 

 radiating ribs, and this peculiarity is common to many recent and fossil species of 

 Brachiopoda. In 1867 Commodore Acton dredged a very great number of specimens 

 in the Straits of Magellan, which he kindly presented to me. These show every modi- 

 fication in shape, from the smooth shell to those more or less distinctly ribbed. Mr 

 Broderip observes that the radiating striae almost disappear in the older individuals. 

 "ViHien quite young the dorsal valve possesses a high Magasella-sha^ied septum and 

 loop. The shell has received several names, and some difference in opinion has arisen 

 as to the one that should be retained. Mr L. Eeeve observes that, "three years 

 before Gmelin gave the name of Anomia dorsata to this species, it was fully 

 described and figured by Chemnitz with the name of magellanica, which had already 

 been given to it in French by DavUa, Favart, and D'Herbigny." Mr Dall is, how- 

 ever, of opinion that, " as Chemnitz was not a binominal writer, his name cannot be 

 retained." The anatomy of this species has been well described by Professor Owen 

 in vol. i. of the Transactions of the Zoological Society. The three dead and 

 separated valves brought back by the Challenger Expedition were nearly smooth, or 

 with the radiating ribs but very faintly indicated, and seem to partake more of the 

 aspect of the variety soiverhyi of King, than of the generahty of specimens of Tere- 

 bratula dorsata. 



