MR J. W. GREGORY ON THE MALTESE FOSSIL ECHINOIDEA. 611 



this genus should not be subdivided, though doubt is expressed as to the value of the 

 characters upon which M. Pomel has based his subdivisions. The writer has previously 

 had to refer to this subject,* and is still unable to accept the genera of MM. Pomel and 

 Meunier-Chalmas. In the case of the present species, at least, it is advisable to leave it 

 in Hemiaster, as the structure of the apical disc is not known with certainty. A specimen 

 labelled as the type of this species came into the possession of the British Museum in the 

 Wright Collection, but this is more depressed than it should be if Dr Wright's measure- 

 ments are correct ; it, however, agrees closely with the figure. This specimen has 

 distinctly four genital pores. 



Dr Leith Adams identified a series of specimens from the Upper and Lower Coralline 

 Limestones, as well as from the Globigerina Limestone, as belonging to this species ; but 

 I have only been able to obtain satisfactory evidence of its existence in the last bed. 



Species 2. Hemiaster scillae, Wright, 1855. 



Synonymy — 



Hemiaster scillce, T. Wright, 1855, "Foss. Echinod. Malta," Ann. Mag. Nat. Hist. (2), xv. pp. 191-193, 

 pi. vii. f. 1. 

 „ „ E. Desor, 1858, Syn. £ch. foss., p. 375. 



,, ,, T. Wright, 1864, "Foss. Echinidse Malta," Quart. Journ. Gedl. Soc, xx. pp. 



483, 484. 

 Opissaster „ Pomel, 1883, Classif. meth. et gen. Ecli., p. 38. 



Type. — Coll. Earl of Ducie. 



Distribution. — Malta — Nodule Seams in Globigerina Limestone. Seam No. 4 at 

 Fommer Eeh. 



Remarks. — The nearest ally of this species appears to be Hemiaster rotundus, Laube,! 

 and the differences between them have been pointed out by Professor Laube. But this 

 latter species Professor Pomel places in Trachyaster, and it seems to me that Hemiaster 

 scillce really agrees more with the diagnosis of that genus than with that of Opissaster ; 

 thus the form is globular instead of cordiform, and there are four (? three) genital pores, 

 and not only a couple. It differs from both genera in the central position of the apical 

 disc. The only specimens in the British Museum Collection do not enable the structure 

 of the apical system to be clearly determined, but it appears to be ethmophract ; and 

 hence the species may be allowed to remain in Hemiaster. 



The largest specimen I have seen is 39 mm. long, 36 mm. broad, and 34 mm. wide. 



Species 3. Hemiaster vadosus, n. sp. Plate II. fig. 6a-d. 

 Diagnosis. — Shape — Well rounded, but with a slight tendency to become hexagonal. 



* " Some Additions to the Australian Tertiary Echinoidea," Geol. Mag., 1890 (3), vii. p. 489 ; and " A Revision of 

 the British Cainozoic Echinoidea," Proc. Geol. Ass., 1891, xi. p. 21. 



t "Ech. oesterr.-ung. oh. Tertiarabl.," Abh. k k. geol. Reiclw., v., 1871, pp. 68, 69, pi. xviii. f. 6. 



