THALASSEMYDID. 1S 7 
Of the second individual examined by Cope the first peripheral is at hand (fig. 193). It 
has an obtuse free outer and an acute free inner margin. The thickness near the proximal 
end and the outer border is 12 mm. At the hinder end (fig. 194) the thickness is somewhat 
less. On the distal half of the bone and near the free margin, or rather, forming the free 
margin, is a low sharp ridge, at which the upper and the lower surfaces meet. The suture with 
the nuchal is oblique, running from the inner border forward and toward the midline, then 
forward and outward, then again forward and toward the midline. The end of the bone was 
somewhat overlapt by the nuchal. The length along the free outer border is about 65 mm.; 
along the free inner border, about 40 mm.; from one extremity to the other, 80 mm. The 
greatest width is 35 mm.; that near the hinder end is 27 mm. 
The peripheral regarded by Cope as the sixth (fig. 195) has a length of about 100 mm. 
A part of the free border is broken away. The bone is triangular in section, presenting thus 
three faces. The inner or visceral face is quite concave the whole length and has in the 
hinder half a deep conical pit for the end of a rib. The bone is about 30 mm. wide. The lower 
face is slightly concave and is 30 mm. wide. The upper face has a width of from 35 mm. to 
38 mm. and it is nearly plane. According to the present interpretation, the bone belongs to 
the right side. All of the free borders are acute, especially the upper inner, and in none of 
them is there any emargination. 
Fics. 193-195.—Lytoloma jeanest. Peripherals. 3. No. 1473 A. M.N. H. 
193. Right first peripheral. 
194. Section near distal end of first peripheral. 
195. Section of sixth? peripheral. Pit shown by interrupted line. 
Accompanying the bones above described is a fragment of a costal which agrees in its 
dimensions with the one mentioned by Cope. Its width is 90 mm., while the thickness 
thru the middle of the width is 11 mm. Cope states that the costals showed no sculpture. 
However, the present costal has its surface broken by numerous pits of varying form and size, 
resembling thus closely the costals of Osteopygis erosus. It is probable that the bone belongs 
elsewhere. 
The peripheral described above as probably the sixth differs so much from the fifth of 
L. angusta that a distinct species is clearly indicated. The ratios of width to length in the 
two bones are very different. The width of the peripheral of L. angusta is contained in the 
length about two and a third times; while in that of L. jeanes: the width is contained in the 
length three and a third times. The results are equally decisive in case both peripherals 
should happen to be fifths or sixths. It is wholly probable that neither of them can belong 
farther backward in the series. 
The various measurements of this bone show that the carapace described by Wieland can 
not belong to L. jeanest. 
Lytoloma wielandi sp. nov. 
Plate 28, figs. 7, 8; plate 29, fig. 1; text-figs. 196, 197. 
Lytoloma angusta?, WirLanv, Amer. Jour. Sci. (4), XVI, 1904, p. 183, plates vi-viii, text-figs. 1-3; 
Ibid., xx, 1905, p. 333, fig. 5- 
Dr. George R. Wieland has, with exprest doubts, referred some lower jaws, the front of a 
skull, and a carapace of a Lytoloma to L. angusta. His specimens are in the Yale University 
collection. The skull bones were secured by Professor O. C. Marsh from the upper Cretaceous 
greensand bed at Hornerstown, New Jersey. The carapace came from Barnesboro. It seems 
evident that these remains do not belong to the species to which they have been assigned, 
and they are here made the types of a new species, named in honor of Dr. Wieland. 
