s 
R. Lydekker—Tertiary Lacertilia and Ophidia. 111 
Générales,” sér. 2, p. 60, gave a woodcut of the cranial scutes of 
another Lizard from the approximately equivalent Phosphorites of 
Quercy under the name of Varanus margariticeps, making, however, 
no reference whatever to Placosaurus. Now if the type specimens 
of these two forms be compared together, there cannot, I think, be 
much hesitation in acknowledging their generic identity ; while it 
is perfectly clear from the presence of dermal scutes that they have 
nothing whatever to do with the Varanide. At a still later period 
Dr. Filhol* described and figured from the Quercy Phosphorites 
an imperfect dentary bone under the name of Palzovaranus cayluat, 
and suggested that it might be the same as the so-called Varanus 
margariticeps ; but since this specimen appears to belong to a true 
Varanus, it will be perfectly distinct from the latter. In the collection 
of the British Museum I find, however, a number of vertebree belong- 
ing to Lizards of medium dimensions, from Quercy (No. R. 428), 
and also others of similar type from Hordwell (No. 32840), 
which agree most nearly with those of certain existing genera of 
Anguide, and appear decidedly distinct from those of the Varanide, 
although there is a great general resemblance between the vertebrae 
of the two families. This would lead to the conclusion that since 
Placosaurus agrees with the Anguide in the presence of dermal 
scutes, the vertebra: in question belong to the Quercy species of 
that genus. I find, moreover, a dentary bone of a Lizard from 
Quercy (No. R. 3877) agreeing very closely with the dentary of the 
existing genera Diploglossus and Ophisaurus; and the presumption 
is therefore very strong indeed that this specimen is likewise 
referable to the Quercy Placosaurus. It appears, however, to be 
indistinguishable from a fragmentary dentary from Quercy figured 
by Dr. Filhol in pl. xxvi. fig. 425 of the work cited under the 
name of Plestiodon (= Humeces) cadurcensis; that genus belonging 
to the family Scincide. That the present specimen is, however, 
not a Scincoid is decisively shown by the absence of the descending 
ridge from the coronoid on the outer aspect of the posterior ex- 
tremity of the dentary, which forms such a characteristic feature in 
that family. Finally, on comparison of a Quercy femur (No. R. 387) 
with the similar specimen figured by Dr. Filhol (op. cit. pl. xxvi. 
figs. 445-446) under the name of Palgovaranus, I find a marked 
resemblance to the femur of the Anguoid genus Diploglossus and a 
wide difference from that of Varanus. 
The foregoing evidence tends therefore to show that all the above- 
mentioned specimens are in all probability referable to the genus 
Placosaurus; which accordingly appears to have been a member 
of the Anguid@g provided with well-developed limbs. There is no 
evidence to show whether the Quercy form is really distinct from the 
typical Vaucluse P. rugosus; but for the present it may perhaps be 
advisable to retain the specific name margariticeps, of which Plestiodon 
cadurcensis appears to be a synonym. ‘The Hordwell form may 
belong to either the Vaucluse or the Quercy representative of the 
genus, if these be distinct. And I may add that the North American 
1 Op. cit. p. 268, pl. xxvi. fig. 434 (1877). 
