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Show 436 PROF. F. J. BELL ON THE TEMNOPLEURIDAE. [June 1, It is with some hesitation that I include in this rather unsatisfactory series the first and second examples, the great difficulty in tbe way of associating them with the larger specimens being the much greater proportional size of the tubercles on the test; other forms, however, present just the same relation, and the difference in the proportional size of the tubercles in examples iii. and vii. is itself sufficiently striking. Two of the specimens in the Museum collection are stated to have been collected at the Cape of Good Hope. The test is sometimes reddish or purplish in colour, and it is not always that all the ocular plates are shut off from the anal area. 2. AMBLYPNEUSTES GRISEUS. (Plate XLI. figs. 4, 5, 6.) The Table just following shows that there is a considerable variation in the proportions of the species; it will, however, be pointed out that these differences are associated with others which led to the possibility of their being different sex-forms. In any case, it is, without a large series of specimens, impossible to see fully how these differences run, and I am convinced that no good would be gained by attempting to affix distinct names to the two forms. Younger specimens than have yet come to hand will resolve some of the difficulties, and an examination of living specimens will do even more. Actinostome. 35-7 311 236 35 33-3 22-8 27-5 22-1 29 20 21-4 PoriferoiiB zone. 1-2 1*9 2 2 2 2-2 2-3 31 2-6 3-5 41 It does not require much observation to see that these measurements point to two distinct series of proportions among forms which by the other characters of their test appear to be most intimately allied: one series, represented by xi., x., viii., and vi., have a small actinostome, a small abactinal area, and a rather wide poriferous zone ; the other, as seen in ix., vii., iv., has the actinal and abactinal areas very much larger and the poriferous zone rather narrower. With these characters two others, that cannot be represented in the Table, are associated; those with the small actinostome have much larger genital pores, and the madreporic plate is much more prominent. I hesitate, however, to separate them, for. ii iii iv vi vii viii ix xi Absolute diameter of test in millims. 14 28 28 28-5 33 35 40 41-5 42 45 56 Height. 89-2 91-4 92-9 90 91-5 75 86*6 85-7 Percentage value of Abactinal area. 214 22-1 16 219 171 22-5 14-4 ' 20-2 14-4 16 Anal area. 11 7-8 8-5 10-2 • 7-2 106 66 75 |