172 REPORT—1874. 
X. MICROSAURIA. 
Dendrerpeton, Owen. 
Skull (figure). Parabolic. Orbits. Circular, central, distant, small*. External 
nasal foramina. “Small, and near the muzzle” (Dawson). Teeth (disposition). 
Premaxillary larger than the maxillary series; palato-vomerine, a close series of 
teeth internal to the maxillary teeth, and larger; Dr. Dawson finds also blunt 
teeth attached to loose bones, which he thinks may represent the vomer ; mandibular, 
“in the lower jaw there was a uniform series of conical teeth, not pte oe en- 
larged toward the front, and an inner series of larger....teeth....” (Dawson). 
Leeth (structure). (D. acadianum) “Those of the vomer are thinly walled and 
simple, the outer series on the maxillaries and intermaxillaries [and eee 
simple and flattened, while the inner series of teeth [in both jaws] are conical an 
plicated” (Dawson). Cranial sculpture. Reticulate and radiate, minute. Vertebre. 
Centra contracted in the middle, deeply biconcave; broad transverse processes, 
tapering to a point at their free ends, have been found attached to some of these, 
and distinct zygapophyses have been observed in others; “there is a large and 
flattened neural spine ;” “there are other [vertebre] with long spines above and 
below” (Dawson). Abs. “Long and curved, with an expanded head, near to 
which they are solid, but become hollow toward the middle” (Dawson); some, 
at least, have a distinct tuberculum and capitulum. ore limb. Supposed by 
Dr. Dawson to have been as large as the hind limb or larger; “the bones were 
hollow....; the humerus, however, was a strong bone, with thick walls and a 
cancellated structure toward its extremities” (Dawson). Hind limb. The compo- 
nent bones, as in the fore limb, are narrowed in the centre and expanded at the 
ends; Dr. Dawson supposes that “the foot must have been broad, and probably 
suited for swimming or walking on soft mud, or both.” Seutes. “The external 
scales are thin, oblique-rhomboidal, or elongated-oval, marked with slight concen- 
tric lines, but otherwise smooth, and having a thickened ridge or margin.....; in 
one of the specimens the scales of the throat remain in their natural position, and 
are seen to - of a narrow ovate form, and arranged in imbricated rows diverging 
from the mesial line” (Dawson). 
D. acapianum, Owen. 
Dr. Dawson’s account of the differences between this species and D. Oweni is 
given below (see D. Oweni). 
Measurements (from Dr. Dawson). 
in. 
aT. COSI oun Forcitapinte ousleieyens. 1ypdei+ ¢e + wait? sapeuetals Came 2°75 
PSEA UHFAL.NIG CLE" OL OTBILS te ceisisic, vig is oisws: ble veusiva ead Rieke Omen 2 
Wa LRO EMMI GRMN Ses cuckjevackeichele ofa cb o's Goin tke eyeitor soy eae 1:33 
ILGZIE 1, CLE TE ARR 5 SABRI In OF SAUNAS TMOG DSO CR Sr Bin. 1 
Bore TMyOR MONE ys. tars tater letetnvalees iaicis toes eieteteneas |e is7¥1 +. (o.< v's « ieice oie eae 1 
Mone thiOtll VerteNreeedr crac ce sm stam MER. cotaes cs coe ee 2:25 
Locality. South Joggins, Nova Scotia. 
References, Lyell & Dawson, Q. J. Geol. Soc. vol. ix. p. 58, tt. ii, iii, [1853],— 
Owen, dbid. vol. xviii. t. ix. fig. 13, t. x. figs, 5, 6, 7 [1862].—Dawson, ¢bid. 
vol. xix. p. 469 [1863].—Jd. Acadian Geology, 2nd edit. p. 362, fig. 142 
[1867]. 
D. Owrntr, Dawson, 
“Differs from D. acadianum in the following particulars :—(1) Its much smaller 
size; (2) its long and hooked teeth....; (8) the greater plication of the ivory in 
the intermaxillary teeth (in D. acadianum these teeth are on the outside simple 
* Larger in D. Oweni than in D. acadianum, according to Dr. Dawson. 
t In Dr. Dawson's ‘ Air-breathers of the Coal Period’ [1863], p. 61, t. vi. fig. 54, the 
vomerine teeth are represented as aggregated into symmetrical lateral masses, which 
follow the outline of the maxillaries, but are most dense towards the middle line, 
