228 
ERIK A : SON STENSIO 
Finally with regard to the tissue in the supporting gill-rays I have been unable 
to undertake a microscopical investigation of this in the species in question, but it seems 
certain that we have here either calcified cartilage or bone. In many recent Teleostomes 
the supporting gill-rays sometimes consist exclusively of cartilage (e. g. in the stur¬ 
geons), while in other they are to a greater or less extent built up of hard tissue, which 
may be either bone or calcified cartilage (Stannius 1846, pp. 114—115; Riess 1881, 
pp. 531—524; Woodward 1985 b, pp. 80, 219). 
D entition. 
The dentition evidently consisted of both bluntly conical and pointedly conical 
teeth, but is not specially powerful. 
The teeth in the maxillary, premaxillary and dentalo-splenial are not preserved, 
but the evidence seems to show that they were pointedly conical. Similar though rather 
small teeth probably occurred on the labial margin of the mixicoronoid as well, while 
the medial side of this bone is quite without teeth. 
The ecto- and entopterygoid have over the whole medial surface closely situated 
small teeth of a bluntly conical shape, and similarly dense, though somewhat larger teeth 
are also found on the parasphenoid and the membrane bone-plates above 
the basibranchials. 
The dentition of the gill-arches is very characteristic. On the me¬ 
dial side (from a morphological point of view the caudal side) of each 
arch it consists of small plates with dense, fine pointedly conical teeth, 
while on the lateral side it is represented by club-shaped gill-rakers of 
the appearance shown in text fig. 73. The distal widened part on each 
of these g-ill-rakers has a number of closely set, fine spines. All the gill-rakers are 
filled inside with white calcite. 
The skeleton of the unpaired fins. 
The anal fin (P. 172) was apparently small and inserted rather near to the caudal 
fin. It consists, as is usual in the Palaeoniscids, of dense, closely jointed lepidotrichia, 
whose number cannot be stated with certainty. 
The dorsal fin (P. 172) is badly preserved. It is situated far forward, its posterior 
part being opposite the ventral fins. The lepidotrichia, whose number cannot be exactly 
established, are densely jointed throughout. 
The caudal fin (P. i 3 4) is distinctly heterocercal and deeply cleft but otherwise 
nothing can be said as to its shape or its relative strength. Its numerous lepido¬ 
trichia show the same conditions as those of the dorsal and anal fins. 
The skeleton of the shoulder girdle and paired fins. 
The shoulder girdle is rather completely preserved, both with regard to the pri¬ 
mary skeleton and the membrane bones. For practical reasons I shall first give here 
an account of the latter bones. 
The suprascapular ( Sscap , PL 3 i, figs. 1, 2, 3 ; PI. 32 , figs. 3 , 4, 5) is found in situ, but is 
very incomplete. The surpracleithral ( Scl , PI. 3 i, figs. 1 — 3 ; PL 32 , figs. 3 —5) and the 
cleithral (Cl, text fig. 74; Pl. 3 i, figs. 1— 3 ; PL 32 , figs. 3 — 5) are both high and large 
