No.412.] REVIEWS OF RECENT LITERATURE. 329 
creatures, even if they were not offshoots from some primitive form 
of shark. 
A novel and somewhat surprising interpretation of the equally 
problematical arthrodires is given, to the effect that they are teleo- 
stomes belonging to the order Actinopterygii. Newberry, it is true, 
imagined a resemblance to exist between Macropetalichthys and 
recent sturgeons ; but we know now that this genus has nothing to 
o with coccosteans, and Newberry totally misapprehended its 
structure. The lack of a shoulder-girdle and lower jaw (properly 
speaking) in all coccosteans, — an anomaly which they share in 
common with ostracoderms, — and the peculiar arrangement and 
mode of growth of the dermal plates, are characters which, to our 
mind at least, are irreconcilable with actinopterygian affinities. 
Although functional “mandibles” and “maxillaries” are often 
present, yet they are evidently only modified dermal plates of the 
same nature as the body armoring; and the former are suspended 
in soft tissues without any articulation with the cranium or other 
bones whatsoever. They are no more homologous with the jaws of 
bony fishes than is the so-called *clavicular" with a pectoral arch. 
Bashford Dean would exclude arthrodires from fishes altogether, as 
Cope did the ostracoderms ; and elsewhere a tendency may be noticed 
looking toward the revival of M'Coy's Placodermata. 
Turning to the elasmobranchs, Dr. Traquair again surprises us 
by declaring that their paleontological history does not throw any 
definite light on the disputed origin of paired limbs or “on the 
question whether the so-called archipterygium is the primary form 
of paired fin in the fish, or only a secondary modification." Never- 
theless, he cautiously admits that *the paired fins of the Upper 
Devonian shark, Cladoselache, as described by Bashford Dean, 
Smith Woodward, and others, seem to favor the lateral fold theory." 
Next follows a very interesting and very learned discussion of the 
Crossopterygii, the Dipnoi, and Actinopterygii, into which, however, 
Space forbids us to enter. His conclusions regarding the first two 
Eroups are that *the Crossopterygii were not derived /row the 
Dipnoi, and that the modern representatives of the latter group are 
degenerate forms; yet as to the immediate ancestry of the Dipnoi 
themselves and the diphyletic origin of the so-called archipterygium, 
we had best for the present keep an open mind." It need scarcely 
be added that this lucid and timely essay of Dr. Traquair's is of 
Prime importance, not only to paleontologists, but to zodlogists 
everywhere. CRE 
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