REMAINS IN THE COAL-FORMATION OE NOVA SCOTIA. 
641 
minute teeth. The mandibles found are not complete, but there are indications that 
there was an ascending process as in II. Daivsoni, but less developed. The narrow¬ 
ness of the dentary bone in Plate 42, fig. 86, is caused in part by the lower posterior 
edge being bent inward at (a), and by the posterior end being broken off above. 
Vertebrae short and stout, and apparently well ossified. Bibs long, with double head 
and much curved. 
Humerus longer than the femur, which is short and stout, if the bone taken for it is 
rightly determined. 
Abdominal scales narrow, oat-shaped; thoracic plate large, broadly oval. 
Length of mandible. 
4 centimetres. 
5 5 
vertebra. 
5 millimetres. 
55 
rib., 
, , . 2'5 centimetres. 
55 
humerus. 
... 1-5 
55 
femur (?). 
... P2 
55 
tibia. 
8 millimetres. 
55 
Six to 
mandibular teeth . . 
seven teeth in 1 centimetre. 
... 3 ,, 
Under the microscope, the bone shows somewhat elongated cells similar to those of 
H. Dawsoni , but smaller. The teeth in cross-section near the base, present a some¬ 
what complex structure, though the dentine is not folded. Next the pulp cavity 
there are straight radiating cells or tubes, coarse and. with lateral canaliculi. This 
structure, which resembles that of H. Dcausoni, extends about half way to the surfa.ce, 
when the large tubes cease and the canaliculi form a dense network. On the outside of 
this is a thick layer of enamel with fine straight canaliculi. A section nearer the 
apex of the tooth would probably show a less thickness of the second or intermediate 
layer. 
8. Fritschia curtidentata, s.n. (Plate 43, figs. 110 to 128). 
[Hylerpeton curtidentatum, Preliminary Notice, American Journal of Science, l.c.~\ 
This species is represented in the collections by two specimens—one well preserved 
and probably adult, the other smaller and less perfect. In 1876, when I possessed 
but one specimen, I referred it to Hylerpeton ; but it differs from that genus in the 
absence of palatal teeth and in the abdominal armour, which consists of long slender 
rods instead of scales. This kind of protective structure, as is well known, occurs in 
Huxley’s genus Ophiderpeton — a creature otherwise very different—and in Cope’s 
Sauropleura, which in. the parts known has much resemblance to the present genus.* 
m Certain species of TJrocordylus described by Huxley and Eeitsch would seem to present forms of 
scales intermediate between the oat-shaped and rod-like types. 
4x2 
