20 SUPPLEMENT TO THE 



Genus — Meganteris, Skcss, 1S56. 



8. Meganteris ? Vicaryi, Z)«y. Dev. Moii., PI. XX, fig. 15 ; and Dev. Sup., PI. Ill, 



figs. 1, la, \b. 



Shell large, marginally nearly circular, about as wide as long; valves very gently 

 convex and flattened. On attaining their full size they become abruptly bent marginally 

 with an inward curve, and at right angles to the plane of their surface, thus forming 

 a wide, flattened, or biconcave border to the shell. Beak small, much incurved ; beak- 

 ridges sharply defined, leaving a flattened space between them and the hinge-line ; 

 foramen concealed under the incurvature of the beak ; deltidium sometimes visible ; surface 

 smooth. Two specimens measured — 



Length 3, breadth 3, depth 1 inch. 



,, 2 „ 2, „ 1 inch 4 lines. 



Obs. — In Plate XX of my Devonian Monograph I gave a figure of an undescribed 

 species that Mr. Vicary had obtained from the Middle Devonian at Woolborough, near 

 Newton Abbot. I then felt, as at present, uncertain as to the genus to which this 

 remarkable shell should be referred. Nothing is known of its interior, and it is with 

 very considerable hesitation that I now provisionally refer it to Meganteris. A dark fine 

 extending from the umbo of the dorsal valve to about a third of its length shows that it 

 was internally provided with a small septum. Since figuring the perfect example in 

 PI. XX of my Devonian Monograph, Mr. Vicary has obtained from the same locality a 

 much larger but somewhat distorted example of the same species, and this has induced 

 me to describe and name the shell after the discoverer of the only two complete 

 specimens at present known. It is very desirable that as soon as a duplicate speci- 

 men shall have been discovered some search for its internal characters should be made. 

 An incomplete valve of the species under description was also found by Mr. J. E. Lee, at 

 Lummaton, near Torquay. 



Genus — Merista, Suess, 1851. 



9. Merista plebeia, Sow.^ sp. Dav., Dev. Mon., PI. Ill, figs. 2 — 10; and Dev. Sup., 



PI. I, figs. 2G to 29. 



At the time I described the exterior of this species nothing further respecting its 

 internal character was known in addition to its being provided with spiral appendages 



