plesiosauridj:. 179 



R. 741. The crown of a taller tooth in matrix; from Folkestone. 

 The convex surface is exposed, and the ridges are widely 

 separated. Purchased, 1886. 



The following specimen is from the " Osteolite" of KursJc, Russia, 

 the probable equivalent of the Gault. 



33246. The crown of a large tooth. Entire teeth from the same 

 deposits are described and figured by Kiprijanoff in the 

 ' Mem. Ac. Imp. St. Petersbourgy vol. xxxi. art. (3, p. 7, 

 pis. i., ii. Presented by Col. Kiprijanojf. 



The following specimen may belong to the present form. 



36173. A bone which is apparently the extremity of the left 

 premaxilla ; from the Upper Greensand of Shanklin, Isle 

 of Wight. Three dental alveoli and a portion of a fourth 

 remain, the first and fourth being very large. There are 

 large cancelli in the diploe. Purchased, 1869. 



**Polyptychodon continuus, Owen l . 

 Syn. Lutkesaurus , sp., Kiprijanoff' 2 . 



Typically the ridges on the enamel of the teeth finer, more closely 

 approximated, and a larger number continuing to the summit of the 

 crown than in P. interruptus. 



Specimens catalogued under the latter heading indicate a transition 

 from the present to the preceding form, and it is highly probable, as 

 suggested by Sauvage :i , that the teeth to which the present name has 

 been applied are merely the anterior teeth of P. interruptus. The 

 type specimen is, however, said to be from the Lower Greensand, 

 where the latter form is not definitely known. The teeth from the 

 "Osteolite" (Gault) of Bussia figured by Kiprijanoff 1 , under the 

 name of LutJcesaurus, appear indistinguishable from those of tho 

 present form. The fragment of a limb figured 5 under the same 

 name has a structure essentially the same as that of Cimoliosaurus 

 portlandicus (fig. 70); if it really belong to the present form it 

 would seem to indicate an immature individual. 



Hab. Europe (England and liussia). 



1 Odontography, Atlas, pt. ii. p. 10, pi. 72. fig. 13 (1841). 



2 Mem. Ac. Imp. St. P6tersbourg, vol. xxxi. art. 6, ]>. 35 (1883). 



3 Mem. Soc. Geol. France, ser. 3, vol. ii. art. 4, p. 28. 

 1 Op. tit. pi. xvii. 



B Ibid. pi. xix. 



n2 



