Fig. 
PLATE XV. 
1. Bysso-arca tumida, /. Sowerby. Right aspect of a testiferous specimen, natural 
size. Tunstall Hill. Belonging to Professor Phillips. 
Umbonal aspect (rather enlarged) of a left valve (testiferous), 
showing cartilage-grooves on the area. Tunstall Hill. 
Umbonal aspect, natural size. Tunstall Hill. 
Umbonal aspect, natural size. Tunstall Hill. 
(The circular hole in one of the beaks is supposed to have been made 
by a carnivorous mollusc.) 
Ventral aspect (natural size) of a testiferous specimen, 
showing byssal opening. Tunstall Hill. 
Right valve, twice the natural size. ‘Tunstall Hill. 
7. Bysso-arca striata, Schlothemm. Right valve (a little enlarged) of a testiferous 
10. Bysso-arca Kingiana, 
specimen. ‘Tunstall Hill. 
Cast of the right valve (natural size), showing impressions 
of the anterior and posterior teeth. Humbleton Hill. 
Belonging to Mr. J. de C. Sowerby. 
Cast, natural size. Humbleton Hill. 
de Vernewl. left valve of a testiferous specimen, natural 
size. . Tunstall Hill. 
Right valve (twice the natural size) of a testiferous specimen. 
Tunstall Hill. 
Umbonal view of the same valve. 
13. Pleurophorus costatus, Brown. Right valve; testiferous, natural size. Tunstall 
HG, 7 
18, 19. 
20. 
Hall. 
Left valve; testiferous, natural size. Tunstall Hill. 
Cast of a right valve (natural size), showmg impressions of 
the anterior and posterior adductor muscles, and 
pallial ditto. Humbleton Hill. 
Interior of both valves (twice the natural size), showing 
anterior adductor muscular impression (@) ; ridge on the 
posterior side of the last (4); and cartilage fulcrum (c). 
Byers’s Quarry. 
Interior of both valves (twice the natural size) of a young 
individual; testiferous. Byers’s Quarry. 
Right valve (natural size) of a smooth variety; testiferous. 
Byers’s Quarry. 
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