MR J. W. GREGORY ON THE MALTESE FOSSIL ECHINOIDEA. 601 



Linn. auct. (the true Echinus reticulatus, Linn. ),* a reference to which heads his list of 

 literature. Leske did not, however, limit his genus with much discretion, and his two 

 other species were a large flat-based Clypeaster and an Echinolampas ovatus. No great 

 stress however was laid by Leske on his third species, and he clearly established the 

 genus for the Clypeasters. Hence Gray, in 1825, abandoned the Clypeaster of Lamarck 

 as a synonym of Echinanthus, and the latter term was henceforth largely used by 

 zoologists. J. MtjLLER,t in 1854, showed that the genus Clypeaster included species of 

 two very different types of internal structure, but he did not follow his discovery to its 

 logical conclusion, and left both groups in the same genus. It was left to Professor A. 

 Agassiz I to apply Muller's discovery to the subdivision of the genus. He restricted 

 Clypeaster to the flat-based forms, with C. subdepressus as the type, while the species 

 with tumid margins he grouped as Echinanthus, with E. reticulatus (Linn.) (i.e., E. 

 rosaceus, Linn., as actually quoted) as the type. According to the 5th of the British 

 Association Eules for Zoological Nomenclature, § one is bound to follow Professor 

 Agassiz, and this one does without reluctance, as his conclusions certainly seem in accord- 

 ance with common sense. His own type of Echinanthus is that which Leske seems also 

 to have regarded as the most representative of the genus. 



In the late Professor Duncan's "Revision of the Genera of Echinoidea" || he has dis- 

 cussed this question at some length, and it is with great regret that I feel obliged to differ 

 from some of his conclusions. Though Professor Duncan admitted that Breynius' use of 

 the term Echinanthus was so general that " it is, therefore, useless to prolong the dis- 

 cussion regarding his priority" (p. 149), nevertheless, in a later section of the work he 

 retains the name, with Breynius as the author, for a genus of Cassidulidce. As he follows 

 Professor Agassiz in restricting Clypeaster to the flat-based large forms, he has founded 

 the genus Diplothecanthus for the tumid species, with Echinus reticulatus, Linn., as the 

 type, and a second new genus, Plesianthus, for Echinanthus testudinarius, Gray. 

 Professor A. Pomel, however, had resuscitated the name Echinorodum (one of Leske's 

 translations of Van Phelsum's terms) 11 for the tumid Clypeasters. It is synonymous 

 with Professor Duncan's Diplothecanthus, except that it also includes Plesianthus. As 

 Van Phelsum's name has been abandoned, M. Pomel was of course within his rights 

 in employing it, and thus it would have precedence over Professor Duncan's name. In 

 fact, if this name were accepted on Van Phelsum's authority, it would be older than 

 Leske's Echinanthus ; but, as Professor Lutken # * has shown, Leske, who first gave it 



* See Loven, " On the Echinoidea described by Linneus," Bihang Till. K. Sv. Vet. Ah Handl., xiii. Afd. No. 5, pp. 

 172-176. 



t "tTberden Bau der Echinodermen," Abh. h Ah. Wiss. Berlin (1853), 1854, pp. 153-157, pi. v. 



\ " Revision of Echini," III. Gat. Mus. Comp. Zool, No. vii., 1872, pp. 306-310. 



§ "When the evidence as to the original type of a genus is not perfectly clear and indisputable, then the person 

 who first subdivides the genus may affix the original name to any portion of it at his discretion, and no later author has 

 a right to transfer that name to any other part of the original genus." — Brit. Ass. Reports (1842), 1843, p. 111. 



|| Journ. Linn. Soc. Zool., xxiii., 1889, pp. 149-151. 



T Classification Me'thodique et Genera des ilchinides vivants et Fossiles, Paris, 1883, p. 68. 

 ** Chr. E. Lutken, Bidrag til. Kundskab om Echiniderne, Vid. Medd. 1863, pp. 116, 117. 



VOL. XXXVI. PART III. (NO. 22). 4 Y 



