OCR Text |
Show 1881.] PROF. F. J. BELL ON THE GENUS ASTERIAS. 507 59. polaris. = V 2 maa'. 60. polyplax = V 2 pat. 61. rarispina = 1 atr. 62. rodolphi = V 1 mat. 63. rubens = 2 ats. 64. rugispina = 1 atr'. 65. rupicola (?) = 1 atr. 66. scabra == V 2 maa'. (?) 67. sertulifera = 1. 68. sinusoida = 2 e. 69 spectabilis = 2 e. 70. stellionura = 2 aaF. 71. studeri - V 2 ma'. 72. sulcifera = 2 c. 73. tenera = 2 ate. 74. tenuispina = V 1 paa'. 75. troscheli = 1 atr'. 76. vancouveri = V 2 ma£. 77. varia = 1. 78. vulgaris = 2 ats*. Characters of Leptasterias, Verrill.-It may well be a fair question to ask, why, when a genus contains so many species, I do not avail myself of Prof. Verrill's generic division of Leptasterias. The answer falls under two heads :-First, the leading distinctive character is the comparatively large size of the papulae; but this is only a step from what we find in species that are still retained in the genus Asterias proper; the presence of a circlet of spines around the madreporic plate is certainly not a characteristic of the Leptasteriads alone, as must have been abundantly shown in the earlier part of this paper; while, further, all specimens of A. muelleri are most certainly not echinoplacid. In the second place, the presence of a large number of species in a genus cannot, of itself, be any reason at all for establishing a number of insufficiently distinct genera. Queri UBet de natura : ita est. For the purposes of descriptive systematic zoology it may be, and is, necessary to break up an enormous genus into smaller convenient working groups; but it is better not to give to such groups titles which have a precise technical value. For the present, at any rate, I think we may retain Gray's genus Uniophora. CHARACTERS OF THE SPECIES OF Asterias FOUND IN THE B R I T I S H SEAS. M y attention was more particularly directed to this subject by the difficulty which I had in coming to any distinct idea as to the characters of A. hispida. Unable to distinguish any forms as such in the cabinets of the British Museum, I naturally turned for assistance to the well-known naturalist whose acquaintance with the marine fauna of our own coasts is only equalled by his kindness and courtesy. To the Rev. A. M . Norman, then, the national collection "owes some specimens of what he distinguishes as A. hispida. In addition to the specimens of A. hispida which he presented to the Museum, Mr. Norman sent for my inspection several other series of specimens from various localities. In the letter with which he honoured me, Mr. Norman hinted that A. hispida and A. violacea should now be united, he expresses some little doubt as to the accuracy of the determination of the specimens collected in the British * [To make this paper as complete as may be, I add a reference to the species (A Spitsbergen^) lately described by Messrs. Danielssen and Koren. It appears to be pentactinid, polyacanthid, and echinoplacid. See Ann. Nat. Hist. (5) viii. p. 66.-F. J. B. July 1st, 1881.] |