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Show 430 PROF. F. J. BELL ON THE ECHINOMETRIDsE. [Mar. 15, I am unable to give any information as to the oculars of £. mean-canus or S. nudus: no mention is made of this character in the diagnoses given in the ' Revision ;' nor are they there figured. Neither species is represented in the British Museum. With regard to the characters of the radius, the number of species on which I have any thing to report is, unfortunately, still smaller; the buccal apparatus of S. franciscanus, S. giBBosus, and S. depressus being wanting from the British-Museum specimens. S. tuBerculatus would appear to be distinguished by the fact that the radius is not notched terminally, while in alBus, armiger, ery-throgrammus, intermedius, and purpuratus it is always so notched ; S. Bullatus rather has the free end of the radius deeply grooved than notched. Characters of ascending and descending Tooth-processes. (a) Both present i. erythrogrammus. (ft) Ascending process evanescent ii. armiger. (y) Ascending process absent iii. alBus. iv. Bullatus. v. droBachiensis. vi. intermedius. ; ._ ; vii. lividus. i viii. purpuratus. ix. tuberculatus. SPH^ERECHINUS. The difficulties which are offered by the great development of the tubercles and the special characters of the gill-cuts in species of this Fig. 2. Eadius of S. granulans, seen from in front. genus have always appeared to me to stand in the way of the view taken by Prof. A . Agassiz, which regards this genus as a subgenus of Strongylocentrotus. A n examination of the buccal apparatus seems to m e to do more than justify this hesitation. The free end of the radius, in place of being merely widened out at its end, presents a strong and deep furcation, each leg of the fork measuring 6 millim., in a radius of which the azgyos piece was 11 millim. long, and the angle so wide as to separate the free ends of the legs by 5 millim. It has not been m y fortune to meet with so aberrant an arrangement in any other regular Echinid save Toxopneustes. |