36 



JAMES A. GRIEG 



[REP. OF THE MICHAEL SARS" NORTH 



At stat. 101 23 Psilaster andromeda were taken which 

 were grouped about 6—10 mm. (9 specimens) and 14 

 —22 mm. (14 specimens). The grouping was not very 

 distinct, however. If we compare this material with some 

 from the Norwegian coast in the Bergen Museum, it 

 appears that the smallest specimens (disc-radius 6—8 mm.) 

 must belong to a year-ciass, different from that of the 

 largest specimens (disc-radius 20—22 mm.) It is further 

 evident that some of the intermediary examples (disc- 

 radius 10—19 mm.), must represent a third year-class 

 with a maximum at 12—15 mm. The smallest indivi- 

 duals must be two years old and the largest about four, 

 and I should be inclined to consider the before-mentioned 

 j ear-classes of Plutonaster bifrons as being of the same 

 age as these. 



The specimens of Bathybiaster robustus taken at 

 stat. 101 are grouped as follows: Two individuals with 

 disc-radius of 11—12 mm., and besides a group of 23 

 individuals with disc-radius of 15—21 mm. This group 

 affords a maximum of 11 individuals at 19—20 mm. The 

 fact that maximum included the largest individuals 

 (there were only three larger examples at 21 mm.)seems to 

 indicate that the two small individuals (11—12 mm.) 

 may belong to a year-class distinct from the rest. 



From the foregoing examples we may thus infer 

 that what has been said before about the deep-sea ophiu- 

 rids of the North Atlantic applies equally to the star- 

 fishes of that region. The latter may also be represented 

 by several year-classes in a locality, whilst only one of 

 them is numerously represented. In my treatise "Nogen 

 asteriders alder og aarsklasser" : ) and "Remarks on the 

 Age of some Arctic and North-Atlantic Star-fishes" 2 ) I 

 have entered more at length upon the subject of the 

 grouping of the asterids occurring in a locality. 



Ophiomusium lymani is a world-wide species, known 

 from the Atlantic, the Pacific and the Indian Oceans, 

 130—3435 m. In the Atlantic where it appears to be the 

 most widely distributed deep-sea ophiurid, it ranges north 

 to 61° 10.8' on the eastern side and to 66° 49' on the 

 western side. 



Ophiomusium planum Lyman. 



Ophiomusium planum, Lyman, Bull. Mus. Comp. Zool., vol. 5, no. 9, 

 1878, p. 218, tab. 3, figs. 46— 48. 



10 /4, stat. 10, 45 c 26' N. 9 r 20' W., 4700 m., yellow mud, temp. 

 2.56° Cel. Three specimens. Disc-diameter 16.5—22 mm. 



8 /c, stat. 53, 34° 59' N. 33° 1' W. 2615—2865 m„ yellow hard clayish 

 mud, temp. 3° Cel. Three specimens. Disc-diameter 15.5— 22.5 mm. 



This species has normally three arm-spines, but as 

 already pointed out by Koehler 1 ), it may have four, of 

 which the uppermost is placed at some distance from 

 the rest. Some of the specimens under discussion had, 

 however, sometimes as many as five spines, of which 

 the three ventral ones stood very close together, while 

 the two others were separated by a space from them and 

 from one another. The mouth-shields likewise seem to 

 be subject to variations. In the smallest specimens their 

 form resembles that of typical Ophiomusium planum, while 

 those in the larger specimens are more similar to the 

 mouth-shields in Ophiomusium armigerum. As, however, 

 the specimens agree with Ophiomusium planum in other 

 characters, I have referred them to that species. 



In the Atlantic Ophiomusium planum is hitherto taken 

 only in the northern part, but is found there on the 

 western as well as on the eastern side. It is distributed 

 on the west Atlantic side from 24° 3' to 37° 56' 20" N., 

 262—4064 m. It was first taken by the "Blake" in the 

 West-Indies, where it was also later found by the "Alba- 

 tross". The same vessel took it also off the east coast 

 of North America. On the east Atlantic side it ranges 

 from 15° 48' to 45° 26' N., 2325—5005 m. It was collec- 

 ted by the "Talisman" of the Cape Verde Is., the 

 Canarys and the Azores, where is it later also taken by 

 the Prince of Monaco. Finally the "Investigator" has 

 taken it in the Gulf of Bengal, 2782—3563 m. 



Ophiactis abyssico/a M. Sars. 

 Amphiura abyssicola M. Sars, Oversigt af Norges Echinoder mer, 

 1861, p. 18, tab. 2, figs. 7—12. 

 28/ 6 stat. 24, 28° 8' N. 13° 35' W., 1365 m. yellow mud, temp. 

 8° Cel. Two specimens. 



> stat. 101, 57°41'N. 11°48'W., 1853 m., hard clay, temp. 

 3.3° Cel. 9 specimens. 



The largest specimen measured: disc-diameter 8 

 mm., length of arm 40 mm. It is thus somewhat larger 

 than Sars' type specimen. 



This species is distributed along the west-coast of 

 Norway as far as Senjen, but the northern limit of its 

 range is 71° 25' ("Voeringen" stat. 200). It was besides 

 found east of Shetland Is., in the Faroe — Shetland 

 Channel, off the west coast of Ireland, on the banks 

 between the Faroe Is. and Iceland and in the Denmark 

 Straits. It is further recorded by Mortensen from the 

 west-coast of Greenland, whereas I have not seen it 

 recorded from the east-coast of North America. The 

 Prince of Monaco took it off the Azores. It ranges 

 therefore from 28° 8' to 71° 25' N. on the east Atlantic 



') Bergens Museums Aarbok 1916—17, Naturvidensk. Raekke no. 1. 

 2 ) Ann. Mag. Nat. Hist., ser. 9. vol. 3, 1919, p. 400. 



') Koehler: Ophiures, Exp. Sci. du "Travailleur" et du "Talis- 

 man", 1906, p. 265. 



