STRATA EXPOSED IN CONSTRUCTING FILTON-AVONMOUTH RAILWAY. 21 
Arcomya cf. (Thracia ?) subrugulosa^ Danker. 
W. Dunker, “ Palseontographica I,” (1847), t. xvii., f. 3. 
Specimens which are in general agreement with Banker’s ligareoccar 
rarely in the Pleiiromya beds. They differ in having the urnbones 
rather more elevated, and the posterior margin more obliqaely trancate. 
Oar shell is allied to the genas Arcomya^ Ag. 
Unicardmm (Lucina) arenacea^ Terquem. 
M. O. Terquem, “Palaeont.’ de Hettange” (1855), t. xx., f. 8. 
This species is distinguished from Unicardium cardioides^ Phillips, 
by its more equilateral and less quadrate form. The beaks are not 
directed forward to the same extent as in the last named shell. 
Myoconcha psilonoti^ Quenstedt. 
F. A. Quenstedt, “ Der Jura” (1858), Tab. iv., fig. 15. 
Casts of a large Myoconcha from the Pleuromya beds are somewhat 
doubtfully referred to this species. 
Astarie obsoleta, Dunker. 
W. Dunker, “ Palseontographica I. ” (1848), t. xxv., fs. 8, 9, p. 178. 
Astartes of rather small size with concentric ridges only in the 
young stage, are referred to this species. They are rare in the White 
Lias but common in the Pleuromya beds. 
Astarte consobrina^ Chapuis and Dewalque. 
M. F. Chapuis and M. G. Dewalque, “Foss, du Luxembourg” (1855), 
PI. xxii., fig. 3, p. 149. 
This Astarte^ often confused with A, obsolela, is quite distinct in 
form, and the concentric ridges are present at all stages of growth. 
It appears in the upper part of the Am. iorus beds, and becomes 
common in the angulatus zone. 
My best thanks are due to Messrs. H. Lovatt & Co., the con- 
tractors for the Railway, for facilities afforded in the examination of 
the sections, to Dr. A. Vaughan for assistance in various ways, and 
to Mr. W. H. Wickes for many valuable suggestions and help in 
the field work. 
