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29 
1872.} nae [Cope, 
A partially complete circle of bones convex on one side, concave on the 
other, was found with the remains of two species of Portheus and one of 
Ichthyodectes. They look like a sclerotic ossification, and as though 
moulded on a globe. They are not segmented as in Reptilian sclerotic 
ossifications, nor do they seem to have been completed circles, 
The femoral bones, or those supporting the ventral fins are preserved 
in Ichthyodectes anaides and a Portheus. They are closely united pos- 
teriorly, the inner margins gradually approximating to the union, which 
is accomplished by the application of the subcylindrie posterior part of 
the bones. In Portheus they are united by a coarse suture. There are 
no posterior processes, but the anterior are long and slender. Each is 
divided, the inner portion being rod-like ; the exterior plate-like. The 
outer is probably the shorter ; exteriorly it rises into an obtuse ridge on 
the lower side, and the plate then expands backwards as well as outwards 
nearly enclosing a large sinus with the base of support of the fin. The 
fin-supporting surface is sub-round, with two exterior and one interior 
articular surfaces, and a projection in the middle, which has one or two 
articular faces of smaller size. The base of the anterior projections is 
‘ather broader in Jchthyodectes than in Portheus. 
Three kinds of spine-like rays or supports of the fins have been found 
in connection with remains of species of this family, and the proper 
reference to their positions and species is as yet in some degree uncertain. 
First. The elegantly segmented compound rays originally referred to 
Piychodus by Agassiz, and described by me under the species Sawro- 
cephalus thaumas, appear to be referable to the genus Portheus, and to be 
Supports of the caudal fin.* Secondly. Spines composed of unsegmented 
rays closely united edge to edge, and arranged like the fulcra at the base 
of the external rays of the caudal fin of recent fishes. That is, the first 
very short ; those succeeding, increasing very regularly in length to the 
last, which forms the apex of the spine. The obliquely truncated 
extremities of these rods form a continuous sharp edge, which is coated 
with enamel, and may be straight, or interrupted with low knobs. The 
former kind belongs probably to Portheus and the latter to Ichthyodectes, 
It is nearly related in character to the spines of Hdestes, the enamel coated 
knobs of Jchthyodectes rising into veritable teeth in the carboniferous 
genus. These spines are unsymmetrical, and belong either to the pectoral 
or ventral fins. To which they should be referred, it is not now easy to 
decide. The living allies of the Sawrodontide do not possess ventral 
Spines, nor do they exist in Physostomous fishes. In the Siluroids, the 
Pectoral fins are supported by strong spines, which remotely resemble 
the present ones in their compound character, 
Third. There are numerous flat, more or less curved, spines or rays, of 
Small diameter compared with the length. One surface is covered with a 
thin, gene rally striate-grooved layer of enamel, and one edge is trenchant. 
One side of this edge is more or less obtusely rugose, or thickened. 
*See Hayden’s Report, /.c., p. 423, where this view is held. 
A. P. S.—VOL. XII.—2P. 
