OCR Text |
Show 1880.] 1'IIOF. F. J. BULL ON THE TEMNOPI.EURID.E. 435 appended Table will show very clearly that the abactinal, anal, and actinal areas rather vary in individuals than grow smaller with age ; in this point the species resembles rather Amblypneustes than Temnopleurus. The specimens vary considerably in colour, being in some cases banded with bright red and altogether devoid of a greenish hue ; in another the bands are not purplish, but of a darker green at the base ; in others the base of the spine is not light green, but is of a dark straw-colour. The variations in height are shown by the measurements to extend within wide limits. Absolute diameter in millims. 16*5 23-5 24 31 36 40 42-5 Height, 78-7 72-3 84-5 67-7 88-8 85 66-1 Percentag* Abactinal area. 21-2 19*1 18-7 19-3 16*6 18-8 i values of Anal area. 10-9 8*5 8-75 8-3 8-6 9*8 Actinostome. 33-3 34 33-7 32-2 27-7 25 341 V. AMBLYPNEUSTES. It will still, I fear, be some time before we shall be able completely to "unravel this difficult genus;" and so far as the difference in size of the genital pores is concerned, a new difficulty is almost as m u c h introduced as old difficulties explained. I have seen no specimen of A. pentagonus, A. Ag. If Codechinus, Desor, is really synonymous with Amblypneustes, the genus will differ from all its allies by passing back as far as the Lower Cretaceous formations ; for even Pleurechinus and Temnechinus are, so far as we yet know, Tertiary forms1. But Codechinus is defined by Desor as having no angular pores, and it is possible that the two genera are distinct. 1. AMBLYPNEUSTES OVUM. i.(?)... ii. (?)... ill iv v vi vii Absolute diameter in millims. 15 21 35 40 42 47 58 Height. 833 88 80-5 102-5 100 100 97*4 Percentage value of Abactinal area. 22 20-3 214 20 27 15 16 Anal area. 10 11-4 9-7 8-3 7*5 8 Actinostome. 43-3 33-3 28-5 28-72 26-1 21*3 21-5 Poriferous zone. 1-5 20 _ l Haudbuch der Paliiontologie (Zitt&l), i. 3, pp. 507-509, and Synop. des Echinides foss. p. 111. 2 This is almost a pentagonal variety. PROC. ZOOL. Soc-1880, No. XXIX. 29 |