1066 REPORT—1885. 
figured as Pliosaurus portlandicus by Owen (‘ Fossil Reptiles’), but ascribed to 
Plesiosaurus Manseli by Hulke (Q. J. G. 8. 1883, Suppl. p. 52). This therefore is 
an additional proof that the primary location of the intermedium is in the 
‘ propodial’ segment of the limb. 
The limb of Sauranodon contains in its next segment four bones, and so probably, 
to judge from its articular surfaces, did that of Phosaurus. That is to say, granted 
that the bones already mentioned are rightly identified, we have in the proximal 
segment of the tarsus a tibiale, a fibulare, and two centralia. In the Edinburgh 
Ichthyosaurus we have one centrale only ; and, moreover, we have.again in the next 
succeeding segment t/ee bones only, whereas we have five in the corresponding 
region of Marsh’s Sawranodon. So far then we haye three longitudinal series of 
bones, and these three rows continue distinct to the distal extremity of the limb. 
Two other longitudinal series of bones exist: one, a somewhat irregular series of 
rounded ossicles, is applied to the tibial side of the limb, commencing immediately 
distal to the tarsus, but not directly articulated with it; the other, commencing at 
the same level, is inserted between the median and external or fibular row. If 
we may consider the ground-plan of the limb apart from these last two series, we 
have here simply three longitudinal series of bones, symmetrically articulated with 
the extremity of a basal segment. While the limb of Sauranodon seemed to be 
a weighty argument in support of Gegenbaur’s theory of the primitively double 
nature of the centrale, the present example seems to me a still more potent argu- 
ment against it; for the common type of Ichthyosaurian limb is undoubtedly 
intermediate between that of the present example and the typical cheiropterygium 
of the higher vertebrates; and we pass from our present case to the typical 
Ichthyosaurus by transverse cleavage of the centrale, and the apportionment of its 
outer moiety to the interstitial digit. 
It is equally easy to pass downwards from this limb to the fin of fishes. 
Assuming the femur to represent the basipterygium, we have here three basalia, 
which by elongation and segmentation may be supposed to have given rise to the 
distal portion of the fin. And the limb has a great though not genetic resemblance 
to that of Polypterus, where the basalia are reduced to four, or as in one specimen 
which I have dissected, actually to three. It need hardly be said that this view 
is wholly incompatible with Gegenbaur’s theories; and indeed Wiedersheim has 
confessed that if the limb of Sauranodon be confirmed, it must lead to the 
complete recasting of our idea of the vertebrate limb. But it remains to be seen 
whether the Dipnoan fin is explicable on this hypothesis. In the fin of Protopterus 
the segment articulating with the pelvis, is, I take it, a true basipterygium. To 
it I find attached two small nodules of cartilage, between which is the main axis 
of the fin: here we seem to have three basalia, one only of which is elongated or 
segmented, as are all in our Ichthyosaurus. While in Ceratodus we are reduced 
to supposing that this one segmented ray has branched laterally, to give breadth 
and strength to the fin. 
5. On the Origin of the Fishes of the Sea of Galilee. 
By Professor Epwarp Hout, DL.D., F.R.S. 
When preparing a memoir for the Palestine Exploration Society on the physical 
history of Arabia Petreea and Palestine I was confronted with two biological 
problems: one, on the origin of the fauna of the Sea of Galilee (or Lake of 
Tiberias) ; the other, on the cause of the extreme dissimilarity between the faunas 
of the Red Sea and Mediterranean, notwithstanding the ascertained fact that the 
seas themselves have been physically connected within very recent times. With 
the former problem I propose here to deal as far as the fishes are concerned ; with the 
latter I shall deal presently. 
The abundance of the fishes which inhabit the waters of the Sea of Galilee is 
known both from sacred and secular history, and has been testified to by several 
recent observers. The characters and habits of these fishes have also been ably dis- 
