172 FOSSIL FISHES OF THE ENGLISH CHALK. 
1. Macropoma mantelli, Agassiz. Plate XXXV, figs. 9, 10; Plates XXXVI, 
XXXVI, XXXVITI, figs. 1 
5. Text-figures 49, 50. 
1822. Amia? lewesiensis, G. A. Mantell, Foss. South Downs, p. 239, pls. xxxvii, xxxviil. 
1835-1844.  Macropoma mantelli, L. Agassiz, Poiss. Foss., Feuill., p. 55, and vol. 11, pt. u, p. 174, 
pl. lxv, a (bis)—d. 
1849. Macropoma mantelli, W. C. Williamson, Phil. Trans., p. 462, pl. xlii, figs. 25, 26, pl. xl, 
figs. 27—30. 
1850. Macropoma mantelli, F. Dixon, Geol. Sussex, p. 368, pl. xxxiv, fig. 2. 
1866. Macropoma mantelli, T. H. Huxley, Figs. and Descrips. Brit. Organic Remains (Mem. Geol. 
Surv.), dec. xii, p. 27, pls. vii, viii. 
1888. Macropoma mantelli, A.S. Woodward, Proc. Geol. Assoc., vol. x, p. 303. 
1891. Macropoma mantelli, A. 8. Woodward, Catal. Foss. Fishes B. M., pt. i, p. 416, pl. xiv, fig. 3. 
1907. Macropoma mantelli, A. S. Woodward, Quart. Journ. Geol. Soc., vol. lxiii, p. 136, pl. viii, figs. 7, 8. 
Type.—Nearly complete fish (Pl. XXXVI, fig. 1); British Museum. 
Specific Characters.—The type species, attainng a length of about 60 cm. 
Leneth of head with opercular apparatus about equalling the maximum depth of 
the trunk, and contained four times in the total length of the fish. All external 
bones ornamented with fine rounded tubercles of ganoine; the cranial roof-bones 
and the cheek-plates exhibiting in part also a coarsely reticulate or spongy surface. 
Operculum not quite two thirds as wide as deep; each gular plate about four times 
as long as wide. Anterior dorsal fin with eight rays; caudal fin with about twenty 
rays above and below. All scales covered with hollow spinelets and elongated 
tubercles of ganoine; on each scale behind the middle of the abdominal region, a 
median horizontal series of two or three spinelets relatively large and prominent ; 
the scales of the lateral line between the lobes of the caudal fin extensively smooth 
and thickened. 
Description of Specimens.—The general proportions of the fish and many of its 
special characters are exhibited by the type specimen in the Mantell Collection 
(Pl. XXXVI, fig. 1), which still remains the most nearly complete example known. 
This is supplemented by numerous important specimens especially in the British 
Museum, the Brighton Museum (Willett Collection), and the Sedgwick Museum, 
Cambridge. There is thus ample material to justify nearly all parts in the 
restoration of the skeleton of the species attempted in Text-fig. 49, p. 173. 
The chondrocranium is extensively ossified, especially in the otic region, which 
has already been described by Huxley, loc. cit., but, as shown by a fossil in the 
Mantell Collection (B. M. no. 4246), there is no firm union between the parietal 
roof-bones and the underlying elements, while, as proved by many specimens 
(e.g. Pl. XXXVIT, fig. 1), there is no ossified interorbital septum. The prefrontal 
(ectethmoidal) region is evidently ossified, but its shape and proportions are 
uncertain. The membrane-bones of the cranial roof (Pl. XXXV, figs. 10, 10a, 
