MACROPOMA. Aa 
fig. 484, the bifurcated inserted portion being restored in outline from another 
example. <A still larger fulcral scale measures 24 mm. in maximum width and 27 
mm. from the apex to the bifurcation of the base. All these scales are deeply 
overlapping, relatively broad and remarkably flat; while their apex is rounded and 
obtuse. Their characteristic ornament is well shown in the figure. The stout 
fin-rays (Text-fig. 48 8) begin to be very closely articulated at a short distance 
from the base. Their superficial ganoine is thick and rugose, but does not always 
extend completely to the edges. No oat-shaped scales for the side of the upper 
caudal lobe can be distinguished. 
Remarks.—Though so imperfect, the fossil thus described is almost certainly a 
fragment of a sturgeon allied to Psephurus and Polyodon. It is curious that no 
other remains of a fish of the same family have hitherto been found in Cretaceous 
formations in any part of the world. 
Horizon and Locality.—Probably zone of Micraster coranguinum: Gravesend, 
Kent. 
Order CROSSOPTERYGII. 
Suborder ACTINISTIA. 
Family Ca@uacantuip’. 
Genus MACROPOMA, Agassiz. 
Macropoma, L. Agassiz, Poiss. Foss., Feuill., 1835, p. 55. 
Generic Characters.—Cranial roof-bones externally pitted and tuberculated ; 
the other membrane-bones externally tuberculated, and the scales ornamented 
with hollow, enamelled, elongated denticles. Maxille with irregularly arranged 
large and small conical teeth ; vomerine and palatine teeth large and clustered ; 
pterygo-suspensorium covered internally with granules, which pass into small 
conical teeth on the lower margin of the bone; dentary toothless ; splenial with 
small conical teeth. The rays of all the fins robust and straight, not expanded, 
and only articulated for a relatively short extent distally ; a double series of small, 
upwardly-pointing denticles on almost all the rays of the anterior dorsal and 
caudal fins ; pelvic fins opposed to space between the two dorsals; anal fin slightly 
behind the posterior dorsal; tail tapering, without supplementary caudal fin. 
Macropoma mantellt, from the English Chalk. 
Type Species. 
