FORAMINIFERA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 1001 



Genus Pelosina, H. B. Brady. 

 Pelosina arhorescens, sp. nov. (Plate I. figs. 1-5.) 



Test vase-shaped, elongate, sub-cylindrical, erect, smooth, and unctuous to the touch, 

 more or less flexible in the living state, rounded at the base, gradually narrowing towards 

 the superior extremity, which is drawn out into a slender main tubular chamber, some- 

 what dome-shaped at its base. 



From about one-third of the test upwards a number of dichotomous tubular branches 

 extend at irregular intervals with graceful curves. These branches open out into the 

 main chamber (Plate I. fig. 2). The wall at the base of each outgrowth is thicker and 

 somewhat swollen, but after a short distance becomes more uniform in diameter. The 

 walls of the main chamber are thick, composed of fine mud deposited on a slender 

 chitinous envelope extending to the terminal apertures of the branching tubes, where it 

 becomes quite thin, and consists of little more than a membrane, so thin and soft that 

 it readily collapses on drying. 



Colour, Vandyke brown. Height of test, IJ to 2 inches (30 to 48 mm.) or more. 

 A few minute filamentous outgrowths come off" from the outer wall of the extremity of 

 the basal portion, and appear in some cases to be tubular, but they are so fragile that 

 they break off" with the slightest manipulation. It is probable that these filaments serve 

 to fix the test in an upright position in the deposit on the ocean floor. 



Dr H. B. Brady, in describing Pelosina variabilis, says specimens of this (mean- 

 ing P. variabilis) or a closely allied organism have been dredged off the west coast of 

 Scotland. The specimens were nearly an inch in length, with walls somewhat flexible, 

 the shape tolerably regular, long and tapering. The superior extremity, which is tubular 

 and much drawn out, is divided into a number of minute branches, each terminating in 

 an aperture exactly as shown in the larger arms of Astrorhiza limicola. It is therefore 

 very probable that Dr Brady had seen a damaged dried specimen of P. arhorescens 

 sent to him by the late Dr David Robertson of Cumbrae, who also drew my attention 

 to the fact that Dr Brady had never seen a living specimen of P. arhorescens when he 

 published his description of P. variabilis. 



Fig. 1, PI. I., represents a typical example of Pelosina arhorescens taken by the trawl 

 on board Sir John Murray's yacht Medvsa, and kept alive by me for five months in a 

 tank at Millport, Cumbrae. During this time it did not move from the position in which 

 it was first placed in the tank, but repaired several of the damaged terminal tubular 

 branches, and displayed the granulated sarcode and ramifying pseudopodia beautifully 

 extended from the terminal apertures. It was sketched in this condition, and afterwards 

 preserved in glycerine (fig. 1, Plate I.), and has been reproduced from the original draw- 

 ing made by my son, F. J. M. C. Pearcey. Figs. 4-5, Plate I., represent a dried broken 

 specimen from the Weddell Sea. Although much damaged, it shows all the essential 

 characters of the specimen from the west coast of Scotland. 



Distribution. — Scotia Station 420, 2620 fathoms, on a deposit of glacial mud or clay. 



