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Show 1881.] PROF. F. J. BELL ON THE ECHINOMETRIDsE. 431 SPHsERECHINUS GRANULARIS. Absolute diameter, in millim. i. 491 ii. 50' iii. 571 iv. 64l v. 70i vi. 78i vii. 85i viii. 36 ix. 75 x. 102 Percentage value of Height. 61-2 62 631 562 68-5 641 541 72-2 56 661 Actinostome. 3(V7 36 35 32-8 29-2 29-5 29-4 36 33-3 28-4 Abactinal area. 18-35 18 15-8 19-2 171 19-2 15-3 16-6 16 156 Anal area. 10 10 8-3 11-7 9-3 10-9 7 8-3 8-6 83 The first seven specimens, coming all from one locality, are very interesting, as exhibiting the range and character of the variations in this eminently variable genus. PSEUDOBOLETIA. This genus has been so amply defined by Prof. Troschel, that it is only necessary to put his definition into English. " Test flattened and curved, thin ; tubercles small; four pairs of pores in an arc ; two ocular plates touch the periproct; rather deep gill-fissures ; auricles with large foramen and low connecting ridge. It is distinguished from Boletia, Desor, by having four pairs of pores in each arc."2 Two species have been described in it-one by Michelin as indiana, the other by A. Agassiz as Boletia granulata. By the latter author Pseudoboletia is recognized as a subgenus, and P. stenostoma and P. maculata of Troschel are stated to be synonymous with P. granulata and P. indiana respectively. There are certainly two species in the British-Museum collection ; and one is just as certainly P. indiana ; the other species is certainly stenostomatous as compared with P. indiana, and even more so than was Prof. Troschel s specimen ; this, of course, may be due to the fact of its being older. When we study it by the aid of the original definition3 of B. granulata-"remarkable for its comparatively long spines; tubercles uniform in size, very closely crowded too-ether,"-we are unable to gain any assistance from the first clause, owing to the absence of the spines ; but the second half of the definition applies very well ; and, on the whole, I am inclined to feel certain that the specimens are representatives of P. granulata. If, however, they are so, they give a somewhat different aspect to the i These specimens were collected at Naples. 2 Sitzb. naturh. Ver. preuss. Rheinl. 1859, p. 96. 3 Bull. M . C Z. i. 2 (1863), p. 24. |