10O FOSSIL TURTLES OF NORTH AMERICA. 



The peripherals have each three faces, an inner or visceral, a superior, and an inferior. 

 Each of them, from the fourth to the ninth inclusive, has a pit for the reception of the end of 

 a rib. Fig. 197 from Wieland represents sections of these peripherals. It will be observed that 

 they grow broader and thinner from the front of the carapace. The dotted line in each repre- 

 sents the depth of the pit. The table, p. 159, gives the dimensions of some of the peripherals. 

 Dr. Wieland has described certain ossicles intercalated between the peripherals along the 

 free borders of his specimen. He suggests that these are a part of the disappearing osteo- 

 dermal covering of primitive turtles. 



The carapace was covered with horny scutes, which have left distinct impressions of the 

 sulci on the various bones. There were, so far as appears, 5 vertebral scutes, 4 pairs of costals, 

 and probably 12 pairs of marginals and a nuchal. The vertebrals are strongly angulated 



laterally where the sulci running down between the costals are 

 given off. The table herewith shows the dimensions of three 

 vertebral scutes. 



How high on the costal bones the marginal scutes rose can 

 not be determined. 



There were preserved with this carapace some fragments of 

 the plastron, but not enough to permit a restoration of it. Wie- 

 land regards the plastron as having been more reduced than it 

 was in Osteopygis, but otherwise much like it. Small pits in the hinder half of the lower 

 inner free margin of the fourth peripheral show that the hyoplastron extended forward only 

 to it. There are no pits to show how far backward the hypoplastron extended. 



The reasons for regarding this carapace as distinct from that of L. angusta are presented 

 under the latter species. 



Genus ERQUELINNESIA Dollo. 



Pachyrhynchns, Dollo, Bull. Mus. roy. d'Hist. nat. Belgique, 4, 1886, p. 130 (preoccupied). 

 Erquelinnesia, Dollo, Geol. Magazine (3), IV, 1887, p. 393. 



Skull resembling that of Caretta caretta, but more elevated and descending more rapidly 

 in front of the orbits. Palate flat, bounded by low cutting-edges, and extending backward to 

 the hinder half of the roof of the mouth. Choanae in the hinder half of the roof of the mouth, 

 their anterior boundary formed by the palatines, which have met behind the palatal plate of 

 the vomer. Lower jaw not beakt. Shell resembling that of Caretta, but more rounded behind. 



Type: Erquelinnesia gosseleti Y)o\\o = Chelone crassicostata Owen. 



For the structure of the palate of this genus the reader is referred to Mr. R. Lydekker's 

 figure of Lytoloma crassicostatum (Proc. Zool. Soc, London, 1889, plate vi). This figure 

 shows that the choanas are placed in the posterior third of the cranium and that the palatal 

 plates of the palatine bones meet each other in the midline behind the vomer and beneath the 

 narial passages. In the article accompanying this plate Mr. Lydekker states that Dr. Dollo's 

 Erquelinnesia gosseleti is identical specifically with Owen's Chelone crassicostata. For refer- 

 ence to other views of the skull and to figures of the carapace of this species, and to the 

 literature, the reader is referred to Lydekker's Catalogue of Fossil Reptiles, part ill, 1889, 

 page 60. On page 26 of this work is presented a figure of the humerus of E. crassicostata. 

 It is evident that the members of the genus had not yet developt a limb adapted for life on 

 the open sea. 



I he following species is assigned provisionally to Erquelinnesia on account of the great 

 length of the symphysis of the lower jaw. This seems to indicate that the choanae were located 

 far toward the rear of the skull, so far that the palatines must have met behind the vomer. It 

 is probable that in Osteopygis the choanae were not removed so far toward the rear of the skull, 



Erquelinnesia molaria sp. nov. 

 Figs. 198, 199. 



This species is based on a lower jaw which is found in the collection of the Academy of 

 Natural Sciences of Philadelphia. It is labeled as being Lytoloma platyops, as having been 

 presented by Rev. L. H. Lighthipe, and as having been secured at Birmingham, New Jersey. 

 It has, therefore, been collected from the upper bed of the Cretaceous greensand. 



