DR. T. DAVIDSON OX EECENT BEACHIOPODA. 201 



The second specimen was dredged by Dr. Gwyn Jeffreys, in nearly the same place, at 

 a depth of 130(5 fathoms, during the ' Porcupine ' Expedition, 1836. It was also dredged 

 by Sir James Anderson in the North Atlantic, wlien fishing up the telegraph cable, 

 in 2400 fathoms depth ; and again by Dr. J. Gwyn Jeffreys during the cruise of the 

 ' Valorous ' in Baffin's Bay, at depths of 1-450 and 090 fathoms. 



Discina atluntica was obtained at seven or eight different localities by the ' Challenger ' 

 Expedition. In lat. 1° 47' N., long. 24° 26' W., attached to Llmopsis aurita, Brocchi, 

 and associated with one example of Megerlia incei'ta, Davidson, at a depth of 1850 

 fathoms. This station is situated between the Cape Verde Islands or Sierra Leone 

 (Africa) and Fernando Noronha (South America). Again in lat. 4° 33' S., long. 120° 

 58' E., depth from 200 to 360 fathoms, attached to volcanic detritus ; also in lat. 34° 

 37' N., long. 140° 32' E., depth 1875 fathoms, associated with one example of Terehra- 

 tula (?) Lain. In lat. 36° 10' N., long. 178° 0' E., depth 2050 fathoms, attached to 

 fragments of pumice-stone; in lat. 0° 33' S., long. 151° 34' W., at a depth of 2425 

 fathoms ; in lat. 33 °31' S., long. 74° 43' W., depth 2100 fathoms, along with Wald- 

 heim'ui JVyvilU; and, lastly, in lat. 12° 8' S., long. 145° 10' E., off Australia, at a depth of 

 1400 fathoms. 



Dr. Alleync Nicholson observes that abyssal or deep-sea forms are usually widely 

 diffused, their range depending chiefly on temperature and being influenced mainly by 

 oceanic currents. 



Obs. I believe I liave seen nearly all the upper valves of this small species hitherto 

 collected, but only one specimen of the smaller valve. Dr. Gwyn Jeffreys, in his paper 

 " On North-Atlantic Brachiopoda," published in the Ann. & Mag. Nat. Hist, for Sept. 

 1870, says (p. 252) that the " arms (labial processes) are furnished with very long aad 

 slender setae or stiff hair-like cilia, which project beyond the edge of the shell on every 

 side to an extent fully equalling its diameter." He meant, or should have said, from 

 the margin of the mantle, not of the arms. The brachial appendages are, as stated by 

 Dr. S. P. Woodward aud myself, curved backwards, returning upon themselves, and 

 ending in small spires directed downwards towards the ventral valve. Prof. Owen, who 

 in 1835 described with much care the anatomy of the genus Discina, says (pp. 155, 156), 

 " Tiie labial processes, or brachia, are scarcely more adapted to protrude externally than in 

 Terehrutula chilensis, the only parts that are free being the short spiral extremities. . . . 

 The brachial filaments, when viewed through the lens, presented an equal cylindrical 

 figure and an entire surface." He also minutely describes and illustrates the two lobes 

 q{ the mantle, and states that "the branchial vessels may be seen in rich profusion on 

 their inner surface." In a highly magnified view of a small portion of the edge of the 

 jnautle he shows the " terminal divisions of the branchial vessels and their setose cilia" *. 



At my request Dr. Halifax, of Brighton, made for me a series of pi-eparations of the 

 mantle of both Llsclnisca lavls and D. atlantica. These last, from sptjcimens brought 

 home by the ' Challenger ' Expedition, showed in the most clear aud admirable manner 

 the highly vascular mantle, fringed witli long horny setic, entirely agreeing with the 



* R. Owen, " On the Anatomy of the Brachiopoda of Cuvicr, and more especially on the Genera Terebratula and 

 Orlkula," Trans. Zool. Sue. vol. i. p. 145, pi. xxii. figs. 2-13, lS3o. 



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