PALZE0XISCID2E. 
441 
greatest depth of the trunk equalling about one quarter of the total 
length of the fish. Head and opercular apparatus small, occupying 
about one-fifth of the total length; external bones striated, the 
stride upon the cranial roof being coarse, irregular, and more or 
less subdivided. Paired fins small, the pelvic pair placed slightly 
nearer to the anal than to the pectorals; dorsal and anal fins equal 
in size, triangular and short-based, the dorsal arising behind the 
middle of the hack, and the anal opposed to its hinder half. Scales 
arge, those of the middle of the flank somewhat deeper than broad ; 
a few series immediately behind the clavicle exhibiting fine posterior 
flirtings and denticulations. 
As pointed out by Giehel and Traquair, this species is truly re¬ 
ferable to Amblyjpterus; and the other so-called species of Pcdceo- 
niscus , here regarded as synonyms, have also been assigned to 
Amblyjpterus by Traquair. The type specimens were obtained from 
the black shales of Kreuznaeh, and it appears to the present writer 
that the various forms named by Troschel from the same formation 
and locality owe their supposed distinctive features merely to dif¬ 
ferences in crushing and state of preservation. The latter series 
has already been identified with “Palceoniscus ” vrcitislaviensis by 
Weiss, who gives an elaborate table of measurements to show the 
great variation in the proportions of typical examples of P. vrcitis- 
laviensis from Buppersdorf, Bohemia. As a rule the last-mentioned 
specimens do not attain so large a size as those from Kreuznaeh ; 
hut there are intermediate forms, and the examples from Munster 
Appel assigned by Agassiz to P. duvernoyi are almost equally 
small. 
The so-called Pcdceoniscus minutus , Agassiz (Poiss. Boss. vol. ii. 
pt. i. pp. 4, 47, pi. viii. figs. 1-3), from Miinster Appel, of which 
the type is in the Strassburg Museum, is probably the young of 
this species. It is provisionally assigned to Amblyjpterus by 
Traquair, Quart. Journ. Geol. Soc. vol. xxxiii. p. 558. 
A very large imperfect fish from the Lower Permian of Semil, 
Bohemia, described under the name of Pcdceoniscus luridus (J. J. 
Heckel, Denkschr. k. Akad. Wiss., math.-naturw. Cl. vol. xix. 1861, 
p. 54, pi. iv.), is also difficultly distinguishable from Amblypterus 
duvernoyi; the specimen is in the Boyal Bohemian Museum, 
Prague. 
Form. Log. Lower Permian : Bhenish Bavaria and Bohemia. 
37775-76. Two typical large specimens in black shale, of unknown 
locality ; one larger than Agassiz’s second type specimen, 
and the other exhibiting well-preserved scales and median 
fins. Purchased, 1863. 
