OCR Text |
Show 1881.] PROF. F. J. BELL ON THE ECHINOMETRID.E. 423 rate, of those purchased at that time from Mr. Gould is a representative of E. suBangularis1. ECHINOMETRA LUCUNTER. Longest axis, in millim. 19 29-5 53 54 59 65 Morphol. axis, in millim 18 27 31 51-5 53 55 63 Percentage value of Height. 444 492 419 58-2 49 58-1 59-5 Actinostome. 50 46-2 403 431 433 42-7 38-8 Abactinal area. 25 23-9 22-5 19-4 18-5 21-8 17-6 Anal area. 11-1 111 11-25 109 9-25 10 103 The use of the percentage method in detecting variations, and the extent of the variations themselves, seem to be well shown in this Table. ECHINOMETRA SUBANGULARIS. Longest diameter, in millim. 14 31 46-2 55 60 Morphol. axis, in millim. 13-25 30 45 53-5 58 Percentage value of Height. 452 46-5 53-2 54-3 Actinostome. 52-6 46-5 455 44-7 40 Abactinal area. 26-7 20 166 15-8 172 Anal area. 9-5 10 "7.4 86 It m a y be well to direct attention to the fact that the longest axis is very little longer than the morphological axis, another point in which Echinometra contrasts very strongly with the two genera which here precede it. ECHINOMETRA VANBRUNTI. Long axis, in millim. 28 57 57-5 Percentage value of Height. 392 49-8 51-3 Actinostome. 46-4 38-6 365 Abactinal area. 196 16-5 Anal area. 10-7 9-5 1 In a conversation with Mr. Howard Saunders I was reminded that there is a Houtman's Abrolhos on the western coast of Australia; and I have now no doubt that the registrar of the specimens in the year 1844 did not sufficiently distinguish between the two localities. |