1886. | OF THE GENUS ATRETIA. 183 
and compressed, bears no resemblance whatever, and exhibits at all 
ages definite generic characters *. 
ATRETIA BRAZIERI, Sp. nov. 
Description.—This pretty little Brachiopod presents all the well- 
marked characteristics of the genus, two short curved slender 
processes, denticulated at their extremities, descend from the small 
narrow hinge-plate of the smaller dorsal valve, and an elevated wedge- 
shaped projection rises abruptly from the central mesial septum of 
the same valve. The presence of this septum is indicated by a dark 
line visible from the exterior of the shell. The shell is small, 
generally longer than wide, triangular in shape, especially in the 
younger specimens. Dorsal valve rounder and not so large as the 
ventral one, slightly flexucus towards the centre at the margins of 
the valves. The ventral valve, owing to the prolongation of the 
beak area, is longer and more triangular than the dorsal one raised 
towards the beak, which is slightly produced and incurved, with a 
triangular foramen commencing beneath its pointed extremity. Two 
elevated ridges extend from the shoulder of the shell nearly to the 
margins of the valves, and there seems to be a slight elevation 
corresponding with the well-marked exterior depression and sur- 
rounded by muscular scars (?) in the exteriors of the ventral valves 
of two specimens I have examined under magnifying-powers. The 
shell is shallow towards the margins, but rounded and deeper near 
the beak. Shell-substance imperforate ; surface smooth, glossy, and 
gleaming, marked with fine concentric lines of growth ; semitrans- 
parent. Horn-coloured or light grey. 
Length 27 lines; width 14 line; depth about 1 line. Another 
specimen measured 2 lines in length by 2} in width; this was more 
flattened and depressed, and the external mesial sinus in the ventral 
valve was less marked. Other specimens were about | line in length. 
Station and Depth.—Eleven specimens and odd valves were 
dredged in twenty-five fathoms in sandy mud off Cabbage-Tree 
Island, Port Stephens, N.S.W., by Mr. John Brazier, who sent five 
specimens to Dr. Davidson, with the remark that they differed from 
all other known Brachiopoda from Australian waters. 
Obs.—Dr. Davidson commemorated Mr. Brazier’s discovery by 
naming the species after him, and I have deemed it my duty to my old 
and valued friend to describe the species under the name he desired 
to give it, as well as I am able. In so doing I wish to call the 
attention of qualified conchologists thereto, and to place on record 
the wide geographical distribution of the genus Afretia, which we 
now know to range in from 25-1750 fathoms, from nearly 70° N. 
? Norr.—I communicated the discovery of the Australian A/retia to the Nor- 
Wegian naturalist, Herr Herman Friele, whu replied, April 19th, that my 
description of the skeleton of A. brazieri is quite typical of the genus Afretia, 
which he cannot consider to be the young of Rhynchonella. He adds the im- 
portant fact that he obtained some fifty specimens of the Atretia gnomon, Jetffr., 
during the Norwegian North-Atlantic Expedition, but no Rhynchonella occurred 
on the same station or in corresponding depths.—Agnes Crane, April 26th. 
