﻿ACTINOPTERI A. 



61 



contour of its margins, and in the closeness of its transverse ornament, but 

 presents some general approximation. 



Aviculopecten dupliciradiatus, cle Koninck, 1 seems distinguished by its closer 

 transverse marks, its double ribs, and its more triangular front wing. 



Avicula immunis, Barrande, 2 has a smaller front wing, and a larger hind wing. 

 Its front wing seems sharper, and the rays on the hind wing are coarser than the 

 transverse striae. The ornament, though much the same in character, seems 

 decidedly finer. It is very nearly allied, but not I think identical. 



Actinopteria eta, Hall, 3 has a larger, sharper, and more closely striated hind 

 wing and coarser ornament. 



Pterinea oblonga, Trenkner,* seems hardly identifiable from its figure and 

 description. In some respects it is not unlike the present shell, but its rays seem 

 coarser. Its wings do not seem to be shown. 



Note. — In naming this species after the late Mr. Tom Roberts, F.G.S., the 

 writer cannot forbear expressing his sense of the great loss which British 

 palaeontology has sustained by his death. He combined with a keen eye and a 

 clear judgment a fund of quiet perseverance and an extensive knowledge both of 

 the literature and the stone records of his favourite science. Had he lived he 

 would doubtless soon have occupied a place as a palaeontologist rivalled by few. 

 That he had not already done this was due to the simple fact of his generosity. He 

 spent his time in helping others, and so he could do little to make the results of 

 his own researches known. The present writer has been under the deepest 

 obligation to him for constant help, guidance, and correction in the course of 

 this work. 



2. Actinopteria hirundella, Whidborne, sp. PI. VI, figs. 5, 5 a, 6, 6 a, and 



PI. VII, figs. 4, 4 a, 4 b. 



1889. Pterinea hirundella, Whidborne. Geo]. Mag., dec. 3, vol. vi, p. 79. 

 ??1889. Actinopteria iianca, Barrois (not Barrande). Faun. Calc. d'Erbray, 



p. 175, pi. xii, figs. 1, 1 b. 



1 1885, De Koninck, ' Ann. Mus. Koy. H. N. Belg.,' vol. xi, pt. 5, p. 239, t. 34, tigs. 1—3. 



2 1881, Barrande, ' Syst. Sil. Bohem.,' vol. vi, pi. ccxxiv, figs. 3, i- 13 , Et. E. 



3 1881, Hall, ' Pal. N. I 7 .,' vol. v, pt. 1, p. 124, pi. lxxxiv, figs. 8—11. 

 1 1867, Trenkner, ' Palaont. Novit.,' pt. 1, p. 24, pi. iii, fig. 52. 



