26 
flattened. The few most preaxial rays rapidly lengthen to the longest, those 
behind gradually shortening ; and although each is divided by a few distant 
transverse joints, there is apparently no distal bifurcation. 
Of the median fins, the dorsal and anal are well shown in the original of 
PI. IX, Pig. 2, and also in the large specimen Xo./ (PI. X, Pigs. 2, a, and iV), 
In the first-mentioned fossil, each fin is nearly equal in maximum deptli to 
the breadth of the trunk at the commencement of its insertion ; and the 
anterior margin gradually slopes backwards to the summit of the fin, whence 
the height diminishes behind, finally ending abruptly with the small terminal 
ray. Both fins arc supported by a series of robust interspinous bones, much 
fewer than the fin-rays ; and three or four of these endoskelctal elements 
appear to be free in advance of the dermal structures (PI. P, Pig. 2, in). All 
the inters])inous bones, as well as the neural and ha3inal arches are only 
superficially ossified, and the soft internal cartilage is sometimes replaced by 
calcite, while in other cases there is no infilling, and the part has consequently 
become crushed or sj)lit. The fin-rays are slightly more than fifty in number 
in tbe dorsal fin, and at least fifty in the anal ; they are broad and flattened, 
longitudinally ribbed, and closely placed proximally, though slightly diverging 
distally ; and all are divided by several widely-spaced transverse joints, 
though only the hinder rays tend to branch towards the extremities. The 
anterior margin of both these fins and the caudal is formed by the pointed 
extremities of the successively lengthening rays ; and there arc no traces of 
fulcra, except in the dorsal of Xo. (PI. X, Pigs. 2, d), where some minute 
points may perhaps be interpreted as such. The caudal fin-rays are 
articulated and bifurcate distally (PI. VIII, Pig. C), and the fin is either 
very slightly excavated in the middle or not forked (PI. IX, Pig. 1). 
ExosheJeton of Trunk . — The four longitudinal series of dermal scutes 
characteristic of the genus Eelonorlti/ncltiis, are especially well shown in the 
original of PI. IX, Pm. 2. The scutes of the median dorsal and ventral series 
are approximately of the same size, and relatively the largest upon the caudal 
pedicle; but tliosc of the lateral line are very much smaller, being only aliout 
one-balf the dimensions. The dorsal and ventral scutes are at least twice as 
broad as long, and bi-laterally symmetrical ; and the anterior margin exhibits 
a wide re-entering angle, while the posterior margin has a corrcsj)onding 
zl-shaped projection, thus rendering the two borders almost parallel. The 
lateral borders of each scute are straight, and also parallel or slightly diverging 
posteriorly; and the external surface is marked by a prominent tubercular 
