160 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 
arib. 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 
Vertebral. Length. | Width. 
2 100 145 not be determined. 
a 110 135 ke . - 
5 a 2 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. 
Pachyrhynchus, Dotto, Bull. Mus. roy. d’Hist. nat. Belgique, 4, 1886, p. 130 (preoccupied). 
Erquelinnesia, Dotto, Geol. Magazine (3), tv, 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. Choanz 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 gosselett Dollo=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 choanz 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 gosselett 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 111, 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. 
The 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 choane 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 choanz 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. 
