TRIASSIC FISHES FROM SPITZBERGEN 
257 
whole with Perleidus altolepis. The only character of any importance that separates the 
two species is the position of the dorsal fin. For in Colobodus altilepis Woodward the 
dorsal fin has its posterior part opposite the anal fin, while in Perleidus altolepis the same 
fin is situated instead so much farther forward, that its anterior part is opposite the 
ventral fins. On the basis of this character alone, however, I did not think I ought to 
set up a new genus for Colobodus altilepis A. S. Woodward, but placed it, at least 
provisionally, under Perleidus. x ) 
The most important characters known for the genus Perleidus in its present definition may 
be summarized as follows. Small or medium sized fusiform or rather high fishes. The external 
membrane bones of the head with well developed ganoine sculpture of tubercles or striae 
or both. The nasalo-postrostral including not only the interrostrals but also certain of the 
middle rostral elements. Lateral rostral elements forming a paired independent plate. Maxil¬ 
lary and mandibula robust. Preoperculum large and wide. Suboperculum high. Branchio- 
stegal radii not specially numerous. Teeth partly pointed, partly adapted for crushing; the 
former variety limited to the premaxillae and the anterior parts of the maxillary and 
dentalo-splenial. All the teeth have as a rule a point which on a 
the teeth adapted for crusting is marked off as a verruca, but 
there are no striae radiating from this. Fins relatively weak. All 
the lepidotrichia, except those of the caudal fin, unjointed for a 
long stretch proximally. The fulcra are fairly robust. The dorsal 
fin situated either far forward and partly opposite the anal fin 
or somewhat farther backward, so that its posterior part is 
opposite the anal fin. Ventral fins situated considerably nearer 
the anal fin than the pectoral fins. The ventral fins with few 
lepidotrichia. The scales on the ventral side fairly low; those 
on the anterior part of the lateral surfaces of the abdominal 
region, considerably higher than broad, decreasing in height to¬ 
wards the dorsum and backwards toward the posterior parts of 
the abdominal region so that they gradually become rhombical in shape. The anterior 
covered area of all the scales narrow or fairly narrow; the exposed surface with an 
almost smooth ganoine covering. The upper margin with an articulatory spine, the 
posterior margin serrated but always more or less entire in its dorsal part. The ridge- 
scales wide, blunt posteriorly. Besides the main lateral line of the body on either side a 
second shorter lateral line extending from the neck to about the basis of the dorsal fin. 
Text fig. 79. 
Perleidus altolepis (Deecke). 
Scales from different parts of the 
body. After the specimens in the 
Senckenberg Museum in Frank¬ 
furt am Main. 
A) From the anterior part of 
the abdominal region. 
B) From the posterior part of 
the abdominal region. 
C) From the caudal region. 
Perleidus woodwardi nom. nov. 
(PI. 28, fig. 3; Pis. 33; 34; PI. 35, figs. 1—3). 
Synonyms: Colobodus altilepis Woodward A. S. Upsala Geol. Inst. Bull. vol. XI, pp. 296—297, 1912. 
« » Andersson, E. Upsala Geol. Inst. vol. XV, 1916. 
Perleidus woodwardi is one of the most common species among the Triassic fishes 
of Spitzbergen. The present material comprises no less than 14 specimens (P. 166 b, 
I ) Stolley has in 1920 (p. 65) also with much hesitation placed the so-called Semionotus letticus O. Fraas 
in the genus Perleidus, but this species, as I have found, may instead probably belong to the genus Dollopterus 
(cf. foot-note on p. 267). 
Stensio, Triassic Fishes from Spitzbergen. 
'33 
