OCR Text |
Show 508 PROF. F. J. BELL ON THE GENUS ASTERIAS. [May 3, seas as being the^t. muelleri of Sars, and he concludes by directing my attention to a remarkable and rare specimen taken at beabam. The questions, then, which are proposed to us are :- (1) The characters of A. hispida. (2) Is A. muelleri, Sars, found on our shores " (3) Is A. muelleri really distinct from A. glacialis? (4) Have representatives of any other species, described or unde-scribed, been found in our seas ? (1) The Characters of A. hispida. With regard to this species, Edward Forbes writes:-" It may easily be passed over as the young of one of the more common species; but it is very distinct."" He gives as the specific character, " Rays short, rounded, spinous. Avenues ovate." It is, however, obvious that, without some further qualification, the shortness of the rays is a character of no significance whatever; the rays in young Asterids are always proportionally shorter than in older forms; as Sars remarks, in describing A. muelleri1, " Bei jiingeren sind, wie bei alien Seesternen, die Arme verhaltmassig kiirzer." What, therefore, we have to know is whether there is any difference, and, if so, what, between A. hispida and A. rubens in this respect. . . The greater and the lesser radii may, as usual, be distinguished by the symbols B and r; the measurements are made in millimetres. A. rubens. Series a. " Seaham, Mr. Hodge." Breadth of ray. i . . 72=11*5, r=3, or 22 = 3*83 r. 3*2 ii. . . B= 9*5, r=3, or 22 = 3*16 r. 2*8 iii B= 7*0, r = 2, or 22=3*50r. 20 Series ft. l'1A. ruBens. St. Maguus Bay, Shetland; deep water." Breadth of ray. i ... 22=11-0, r=4*0, or 22=3*6 r. 3*0 ii 22=9*5, r=3*0, or 22 = 3*16 r. 31 iii. . . B= 8*2, r=2-6, or 22=3*15?*. 2*5 iv 22= 6-5, r=20, or 22 = 3*25 r. 2*0 A. hispida. Series a. "Oban, Mr. D. Robertson." Breadth of ray. i. . 22=19*5, r = 8*0, or 22 = 2*437 r. 9*0 ii 22=15*0, ?* = 6*2, or 22 = 2*419/*. 6*2 iii 22=12*0, r=6*0, or 22=2*0 r. 5*0 iv 22=11*0, r=4*2, or 22=2*619r. 5*0 Series ft. Outer Skerries, Shetland. Breadth of ray. i 22=170, r=5*0, or 2? = 3*4r. 6*0 ii 22=15*5, r=4*5, or 22=3*4 r. 4*5 iii 22 = 12*0, r=4*0, or 22=3*0 r. 4*5 1 Faun. litt. Norv. p. 56. |