part 1] of the MIOCENE or CErioK. 595 



Although all the specimens are imperfect, I select one (Brit. 

 Mas. L. 28750) as a holotype, the other six (L. 28751-56) being- 

 para types. 



This is one of a small group of species in which there is only 

 partial development of the most characteristic features of the 

 genus Spondylus — the great size of the cardinal area, especially 

 in the right valve ; the wide separation of the umbones ; the 

 strongly inequivalve character ; the diversity of the ornament on 

 the two valves. As all these features are obviously adaptations to 

 the sessile habit, the species which show them but feebly are 

 simply a group of less specialized forms, and do not necessarily 

 possess any such close mutual relationship as would be implied by 

 the separation of them as a sub-genus or section. Among these 

 species are the recent S. imperialis Chenu, also recorded as a fossil 

 from Java, and the Sind fossils S. rouaultl and S. tallavic/nesi 

 A. & H., which all agree in having at intervals strong ribs with 

 a greater development of spines. These may possibly form a genetic 

 series, but the spiny character is much more fully developed in 

 the first-named species. S. waylandi differs from these in the 

 more uniform character of the ribs. Fuchs (in Zittel, 1883) 

 figured two imperfectly preserved Spondyli from Siwa, which 

 present decided resemblances to S. waylandi. His S-pondyhis sp. 

 (pi. viii, figs. 7 & 8) is smaller, narrower and thicker, and more 

 decidedly globose, but the ribbing seems to be very similar; while 

 his S. sp. cf. crassicostatus (pi. viii, fig. 13 own 14) seems to have 

 the inflated-lenticular form, but is rather narrower, and there is a 

 suggestion on the cast of an alternation of one strong with several 

 weak ribs. 



Age. — Miocene, Vindobonian. 



Type-locality. — Minihagalkanda, Southern Province (Ceylon). 



Amtjsium stjbcob^eum (A. d'Archiac & J. Haime). 



1853. Pecten comeus A. d' Archaic & J. Haime, non J. Sowerby, 181S ; 

 ' Description des Animaux Fossiles dti Groupe Nummuliticjue de 

 rinde ' p. 269 & pi. xxiii, figs. 10 a, b, c, 11. 



Although the four specimens from Minihagalkanda are all im- 

 perfect, there can be little doubt as to their identity with the species 

 of d'Archiac & Haime. Those authors, while referring their Sind 

 specimens to Pecten corneas Sowerby, were very doubtful of that 

 reference, on account of the smooth exterior and radially marked 

 interior. Therefore they proposed the trivial name subcorneus, in 

 case of need. These characters which distinguish the Sind species 

 from P. Cornells are not simply specific but generic, being the dis- 

 tinctive features of Amu si u in. 



Of the recent species of Amusium (all Indo-Pacific) the fossil 

 form is nearest to A. japonieum (Grmelin) ; while it is also com- 

 parable with A. placunoides (K. Martin) from the llembang 

 i ( )lder Miocene) of Java, and Burdigalian of the Andaman Islands. 

 From both these species it appears to differ in the closer crowding 



