THE BRACHIOPODA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 147 



DESCRIPTION OF SPECIES. 



The literature in the main is restricted to the more important papers. Further 

 synonymy will be found in DAVIDSON'S Recent Brachiopoda (1886-1888); FISCHER 

 and OEHLERT (1892) ; and BLOCHMANN (1912). 



Pelagodiscus atlanticus (King). 



Discina atlantica, King, 1868, Proe. Nat. Hist. Soc. Dublin, vol. v. pp. 170-173. 



., 1880, Davidson, " Challenger" Report, pp. 62 and 65, pi. iv. figs. 17-18. 



Discinisca atlantica (King), 1888, Davidson, Man. Recent Brack., pt. iii. p. 200, pi. xxvi. figs. 18-22. 

 ,, ,, 1891, Fischer and Oehlert, Exped. Scimt. du " Travailleur " et du 



"Talisman," Brachiopodes, p. 120. 



,, Section Pelagodiscus, 1908, Dall, Bull. Mus. Comp. Zool., vol. xliii. p. 440. 



Qiscinisca , 1911, Eichler, Deutxchen S.-P. Exped., xii., Zool., iv. p. 87, pi. xliv. fig. 22. 



Station 417 ; lat. 71 22' S., long. 16 34' W. (off Coats Land, Antarctica). 

 Depth, 1410 fathoms. March 18, 1904. Sea bottom, blue mud and stones. 

 Temperature 29'9 F. 



Obs. Four upper valves of this interesting species were trawled at this station. 

 The largest specimen measures 675 by 6 mm.; the others, 5 by 5, 475 by 4, and 3'5 

 by 3 '5 mm. respectively. 



All are in a good state of preservation. The shell is thin, semi-transparent, 

 yellowish-brown in colour, and marked by numerous close-set concentric growth 

 lines. The protegulum in each example is well defined, and situated somewhat 

 posteriorly. 



Pelagodiscus (formerly Discinisca) atlanticus is a typical cold-water species with 

 a bathymetric range from 200 to 2425 fathoms. Its geographic range is almost world- 

 wide, as it is known from the North and Mid-Atlantic Ocean, the Pacific, and off 

 Australia. Some seven or eight different localities were established for it by the 

 Challenger Expedition. 



Off Valparaiso it was obtained by this Expedition in 2160 fathoms, on a mud 

 bottom ; temperature 34 F. 



It has also been taken south-west of the Galapagos Islands, in 2035 fathoms ; 

 temperature 3 5 '3 F. (Albatross). 



As mentioned in the prefatory remarks, its probable existence in Antarctic waters 

 has recently been alluded to by EICHLER (1911), who describes two larval forms of a 

 Discinoid from a depth of about 1640 fathoms, Kaiser Wilhelmland II. These appear 

 to have strong affinities with P. atlanticus, and in all probability are referable to this 

 widely dispersed form. 



The present discovery of the species well within the Antarctic Circle is highly 

 interesting, as it increases the known range to a considerable extent geographically, 

 though not bathymetrically. 



(ROY. SOC. EDIN. TRANS., VOL. XLVIII., 369.) 



