432 CLASSIFICATION OF DEVONIAN FISHES 
last-named genus. The second dorsal is over the anal, and the 
caudal fin is rhomboidal and diphycercal. 
On the other hand, Osteolepis, though similar to Dzplopterus in 
many essential respects, has a very inequilobed tail, much like that of 
Glyptolepis. But in Osteolepis, as in its most nearly allied genera, the 
cranial bones and the scales are quite smooth. The three occipital 
plates of the skull remain distinct, but the other bones of the roof 
of the cranium have coalesced, so as to form two bucklers, an 
anterior and a posterior ; in which, however, the outlines of the 
primitive cranial bones, which have, on the whole, an arrangement 
similar to that which obtains in G/yptolemus, are traceable. There 
EES = 
SES 
N 
Fig. 8. Restoration of Os¢eolepis (after Pander). 
are no lateral jugular plates, but the principal jugular plates are 
separated, anteriorly, by an azygos rhomboidal plate. 
The family of the SAURODIPTERINI, characterized by its two. 
dorsals ; less acutely lobate paired fins; jugular plates and no bran- 
chiostegal rays ; smooth scales and cranial bones (among which last 
are three distinct occipital plates, while the other cranial bones have 
more or less coalesced), is thus very distinct from, though allied to, 
that of the Glyptodipterini. It comprises not only the genera 
Osteolepis, Diplopterus, and Triplopterus (?), but also, as I believe, 
a genus which has a later range in time than these, viz., the 
Megalichthys of the Coal, although the want of acquaintance with 
the fins of this genus renders my conclusions as to its affinities 
less secure than I could wish Agassiz does indeed affirm that 
Megalichthys has lobate fins, in a passage cited above (p. 427); but as 
he merely mentions the fact incidentally, I do not like to lay too much 
1 Sir Philip Egerton long since arrived at and published this conclusion in his arrangement 
of the Fossil Fishes in Morris’s Catalogue. More recently Prof. Pander expresses the same 
conviction in the following terms: ‘Sehr gerne méchten wir aber ein anderes Genus noch 
‘*7u den Saurodipteridee bringen, das durch den Bau Seiner Koptknochen ; durch die Gestalt 
‘*seiner Schuppen, seiner Zahne und hauptsachlich durch die mikrospische Structur seiner 
“‘harten Theile sich eng an Osveo/eopzs anschliesst und aus der Kohlenformation herstammt. 
“Es ist der Genus AZegaléchthys, von dem wir leider die Beschaffenheit und Lage seiner 
‘Flossen gar nicht kennen.”—Pander, I. c., p. 5. 
