T. Davidson — On Tertiary Brachiopoda. 157 



terminations are broken, we cannot say wlietlier or not they became 

 attached to the central vertical septum. Two small curved crura 

 project also from the above described lamella, as seen in Fig. 12. 

 From under the middle of the hinge-plate a small ridge extends 

 along the bottom of the valve to about half the length of the shell, 

 and which, as it nears the middle of the valve, forms a high tri- 

 angular-shaped vertical plate, almost perpendicular in front. To 

 each side of the slanting top, and facing the hinge-plate, are two 

 small triangular plates united posteriorly, separate and angular 

 anteriorly. Large muscular impressions are also observable on 

 either side of the bottom of the valve, close to the vertical septum 

 (Fig. 11). In the interior of the ventral valve two strong teeth 

 project from the base of the fissure, and a narrow vertical plate 

 divides the larger portion of the beak into two portions. 



M. Dewalque did not describe or illustrate his genus and species, 

 he simply gave it the name of Mannia, and has requested me to 

 point out its characters ; but this cannot be done satisfactorily until 

 we are in possession of a specimen showing the complete interior of 

 the dorsal valve. 



About thirty specimens of this small species were collected by M. 

 Dewalque from the top of the Miocene beds (Sables Noir du Systeme 

 Diestien), at three miles east of Antwerp. 



12. Rhynchonella Nysti, n. sp.^ PI. VII. Fig. 17. 



Of this interesting species two ventral valves only were found by 

 M. Nyst in the "Scaldisien" "sables gris'' (Crag) of Antwerp, We 

 cannot therefore give a complete description of the shell. These 

 valves are triangular in shape, and measure from four lines in length 

 to something less in breadth. Under the angular beak may be seen a 

 foramen with two narrow labial deltidial plates. The mesial sinus 

 occupies about one-third of the breadth of the shell, and commences 

 at a short distance from the beak. About seventeen strong angular 

 ribs cover its surface, and of these some few bifurcate. The surface 

 is also crossed by equidistant scabrose projecting lines of growth. 

 In external shape and character it approaches to some recent ex- 

 amples of Eh. nigricans. 



13. RnYNCHOsEhLA psiTTACEA, Liime (?), PI. YII. Fig. 18. 



Two incomplete and worn valves of a Bhynchonella here, with 

 some uncertainty, referred to R. psittacea, were found by M. Nyst 

 in the etage Scaldisien " Sables Gris " (Crag) of Antwerp. Their 

 almost smooth surface, and absence of the fine radiating strife peculiar 

 to B. psittacea, render their identification uncertain. They approach 

 also in shape and character to some examples of Bh. hipartita of 

 Brocchi, as well as to the recent Bh. lucida of Gould. 



In addition to the thirteen Belgian Tertiary species above enume- 

 rated, M. Nyst sent me for examination two other forms (PL VIIL 

 Figs. 9, 10), which he states to have been derived from tlie Assise 

 Landenien (= Plastic Clay) of Chercq, near Tournay. To one of 

 them. Fig. 10, he gives the MS. name of Terebratulina Woodi. The 

 other is a Terebratula, bearing much resemblance to certain forms of 



