SUPPOSED MICROSAURIAN SPECIES OF UNCERTAIN RELATIONSHIP.
The following three species are so unusual and so incompletely known that
they can not be considered with any of the above families: _Brachydectes
newberryi_ Cope, Linton, Ohio; _Amblyodon problematicum_ Dawson, Nova
Scotia; _Proterpeton gurleyi_ Moodie, Danville, Illinois.
=Genus BRACHYDECTES Cope, 1868.=
Cope, Proc. Phila. Acad. Nat. Sci., 1868, p. 214.
Cope, Trans. Am. Phil. Soc., 1868, p. 14.
Cope, Geol. Surv. Ohio, II, pt. II, p. 388, 1875, pl. xxvii, fig. 2.
Type: _Brachydectes newberryi_ Cope.
Cope (Geol. Surv. Ohio, vol. II, pt. II, p. 388, 1875), says:
"This genus is indicated by two rami of a mandible and a portion of a
premaxillary only. These, when compared with those of _Œstocephalus_
and _Tuditanus_, from the same locality, and with others described by
authors, are so much stouter, i.e., shorter and more elevated, that
they evidently belong to a genus unlike either. The genus further
differs from _Œstocephalus_ in having the teeth of equal size to the
posterior part of the series; that is, to the base of the elevated
coronoid process. The teeth are elongate cylindrical cones, with their
acute tips turned a little posteriorly. The fractured ones display a
large pulp cavity. The three premaxillaries preserved are similar, but
without curvature at the tips. They do not exhibit striæ or any other
sculpture.
"So far as the remains known go, the genus is nearer _Hylerpeton_
than any other. According to Dawson, that genus is provided with a
large canine-like tooth, at the anterior extremity of the maxillary,
on the inner row, which is inserted into a distinct socket. No such
tooth appears among those of this genus. The latter does not give any
indication of the very elevated coronoid process of _Brachydectes_,
though the external portion of the dentary bone in that region being
lost, little can be said about it."
=Brachydectes newberryi Cope.=
Cope, Proc. Phila. Acad. Nat. Sci., p. 214, 1868.
Cope, Trans. Am. Phil. Soc., 1868, p. 14.
Cope, Geol. Surv. Ohio, II, pt. II, p. 388, pl. xxvii, fig. 2, 1875.
Type: Specimen No. 8604 G, American Museum of Natural History.
Horizon and locality: Linton Ohio, Coal Measures. Cope (Geol. Surv. Ohio,
vol. II, pt II, p. 388, 1875) says of this form:
"The species is represented by one nearly perfect ramus mandibuli, one
dentary bone and one premaxillary, probably not complete.
"The dentary bone appears to have been attached by suture to the
articular and angular, as its free margin has very much of the outline
of that suture in _Amphiuma_ and lizards. The coronoid process
would also seem to be a part of the same bone as in _Amphiuma_ and
_Menopema_, and not composed of the coronoid bone as in lizards. It
rises immediately behind the last tooth, and displays no suture.
"The lower portion of the dentary is prolonged into an acute angle.
This is separated by a deep and wide concavity from the superior
posterior prolongation, which is obtuse, and rises at once into the
coronoid process. Teeth on this dentary, seven; the same number is
on the preserved ramus; this number is suspected to be complete, or
nearly so. The teeth terminate at the obvious termination of each
ramus, which is, it is true, slightly obscured. These teeth are the
longest in the Microsauria in relation to the depth of the ramus,
equaling the largest in _Œstocephalus_. They are doubtless exposed,
as are some of those of the last-named genus, by the splitting away
of the outer parapet of the dentary bone. As no traces of alveoli
have been thus rendered visible I suspect the dentition to have been
acrodont, as in some existing Batrachia.
"No external surface of the mandible remains, but there are no
impressions of sculpture on the matrix. A little external face of the
premaxillary displays none.
"The species is dedicated to Professor John S. Newberry, the able
director of the Geological Survey of Ohio, and discoverer of most of
the Batrachia herein described."
Measurements of the Type.
mm.
Length of ramus of mandible (imperfect) 22
Depth at last tooth 5
Length of exposed tooth 3.5
Length of dentary 16
Depth at coronoid process 7.5
Depth at first tooth 3
=Genus PROTERPETON new genus.=
Type: _Proterpeton gurleyi_ Moodie.
Known from a single vertebra. Spine very high and heavy, the neural canal
large.
=Proterpeton gurleyi new species.=
Type: Specimen No. 13,296, Walker Museum, University of Chicago.
Horizon and locality: Coal Measures near Danville, Illinois.
The vertebra, as preserved, is well characterized by the figure (plate
22, fig. 2). The spine is high and heavy, the neural canal is large, and
the centrum reduced. The form is very unusual. It is apparently from the
cervical region, as there are no indications of zygapophyses, transverse
processes, or hæmal arches, although they may have been abraded;
apparently not, however. The type specimen was discovered near Danville,
Illinois, about the horizon of the Danville coal, so that it is quite high
in the Allegheny series of the Pennsylvanian and of about the same horizon
as the phalangeal bone from Breeze, Illinois, which may be provisionally
associated with this form. There is no assurance that Proterpeton gurleyi
is an amphibian. The vertebra may have belonged to a fish.
Measurements of the Type of Proterpeton gurleyi Moodie.
mm.
Entire height of vertebra 24
Width at side of neural canal 21.5
Width of neural canal 13
Height of neural canal (crushed?) 6.5
Width of vertebral centrum anteroposteriorly 5.5
Height of neural spine from top of neural canal 9
=Genus AMBLYODON Dawson, 1882.=
Dawson, Phil. Trans. Roy. Soc. London, pt. 11, p. 644, pl. 40, figs.
57-61, 1882.
Type: _Amblyodon problematicum_ Dawson.
This genus was described by Dawson in 1882 from very imperfect remains. He
says that it is "characterized by stout cylindrical teeth, blunt at the
apices; but otherwise imperfectly known."
=Amblyodon problematicum Dawson.=
Dawson, Phil. Trans. Roy. Soc. London, pt. II, p. 644, pl. 40, figs.
57 to 61, 1882.
Type: Specimen No. 3061-10, Peter Redpath Museum, McGill University.
[Illustration: Fig. 38.--Skeletal elements of _Amblyodon sp._ from the
Coal Measures of Nova Scotia. _a_, tooth, × 25; _b_, section of tooth, ×
25; _d_, fragment of thoracic plate; _f_, shaft of limb bone; _e_, rib.]
Horizon and locality: Coal Measures of Nova Scotia.
A fragment of a jaw 1 cm. in length has 10 cylindrical teeth, simple and
smooth, with large pulp cavities and rounded regularly at the apices.
With these are 4 vertebræ of the usual type, measuring together 1 cm.
Fragments of cranial bones also occur and are obscurely pitted. There is
also what seems to be the shaft of a limb bone and a few oval scales. A
flat and somewhat rhombic bone, with a style at one side, may possibly be
a thoracic plate or possibly a parasphenoid.
The material is too scanty for any satisfactory description of this
animal, but it is provisionally named _Amblyodon problematicum_.