40 TRIASSIC FISHES AND PLANTS 
the head. At Sunderland, . tenuiceps is the prevailing species, and, though 
often ovoid in outline, may always be distinguished by its humped back 
and huge dorsal scales. he fins are also larger than those of either of the 
above mentioned species. 
IscHYPTERUS LINEATUS, N. Sp. 
Pl. XI, Figs. 1, 2. 
Fishes six to eight inches in length; outline when perfectly preserved 
uniformly arched above and below ; head relatively large, contained about 
four times in entire length, broadly conical in outline; fins all large; 
fulera arched; scales of dorsal line spinous and strong, but less developed 
than in J. tenuiceps; ribs and interspinous bones frequently preserved ; 
‘scales on sides thick and strong, arranged in continuous rows from the head 
backward, so as to give a lined appearance, which has suggested the spe- 
cific name. 
The fishes of this group are not easily separated from some of their 
associates; some individuals resembling those of J. /enticularis; but in these 
latter the outline is more symmetrical, the fins smaller, the scales more deli- 
cate, particularly those of the dorsal line. On the other hand, they approach 
through the smaller individuals the group to which I have given the name 
of I. elegans; but these latter are smaller, the arch of the back is higher, the 
head more depressed and acute, the fins and scales are more delicate. 
Still another variety, including the narrower forms, comes nearer to I. fultus. 
On the whole, however, this group of long ovoid fishes, from two to three 
inches wide, are distinguishable at a glance from those which have the nar- 
row lanceolate outlines of I. fultus, a fish which, though attaining the length 
of six to seven inches, never passes a width of an inch and a half. 
The fishes to which I have given the name of Jschyplerus alatus, and 
have represented on Pl. VIII, are perhaps most like those under consid- 
eration, and I hesitated long before separating them; indeed, it is probable 
they will be found to run into each other, so that they must be regarded as 
varieties of one species. By comparing the figures now given, however, it 
will be seen that in the fishes I have called Z. alatus the fins are stronger, 
and the dorsal is placed farther forward, its anterior margin being just mid- 
