1884.] . Batrachia of the Permian Period of North America. 39 
lower jaw has no posterior projecting angle. There are mucous | 
grooves on the skull. The abdominal scales are oblong and in 
close contact with each other. 
Cricotus heteroclitus was first found in Illinois, and afterwards in 
Texas. It is a more elongate animal than any of those described 
in the preceding pages, and it was furnished with short, rather 
stout limbs. It probably reached a length of ten feet, as my 
best preserved specimen, which is not the largest, measures about 
eight feet. It has an elongate triangular skull, eleven inches by 
six behind, with a singularly long, narrow, depressed muzzle, 
whose extremity overhangs the lower jaw completely. There are 
three pairs of mucous grooves; one is on each side of the roof of 
the muzzle, and runs out on the edge of the upper jaw, where 
it overhangs the extremity of the corresponding ramus. The 
second descends from behind the orbit, and running parallel to 
the edge of the upper jaw, joins the first at the usual position of 
a canine tooth in other forms. The third extends along the in- 
ternal inferior edge of the mandibular ramus. 
This species was probably aquatic in its habits. A smaller 
species, the C. gibsoni, has been described from Illinois. Its cau- 
dal vertebrze are of more elongate, cubical form than those of the 
C. heteroclitus. 
EXPLANATION OF PLATES. 
PLATE II. 
e Sy ase, omy Cope, vertebral column, one-fourth natural size, the upper fig- 
m the left side, the lower figure from below. The four- sections of the 
Ba represented are parts of the same individual. 
Prare IIT. 
oe meer Cope, pelvic arch and femur, four-fifteenths natural size, be- 
o the individual figured in Plate 11. Figs. 11-14 pelvis ; H, left side; 
on poate I3, posterior view; 14, from below. Figs. 15-19, femur; 15, ante- 
rior view; 16, posterior view; 17, proximal view; 19, distal view. 
PLATE IV. 
Trimerorhachis insignis Cope, part of vertebral column flattened by pressure, of 
probably one individual, natural size. The upper figures ete sa ) from the 
right side; the lower (exc ept d) from below. Figs. a-d, atlas and axis, t 
former with double s eid the latter with single Ascot Fig. 4, 
anterior view; Fig. d, posterior view. 
PLATE V. 
Cricotus heteroclitus Cope, part of skeleton of one individual, tae Figs fand g, 
two fifths natural size. The vertebra on the agait Ho wi clude the posterior 
extremity of the dorso-lumbar series of the as r besertéd! viewed 
partly from above. Fig, a, first cervical aar Tasg pies face; 4, the same 
attached to front of first cervical ayia. lateral view ; c, four cervical centra 
Separated by intercentra, partly from below; æd, e, caudal are from below ; 
caudal vertebræ siaal right sf i "Fi i ond. g, specimens of the same from 
Illinois, anterior v ws ; f, a dorsc-lumbar intercentrum ; ‘ Eye akata Hoste tae a 
with bases of ere bone; “ah two-fifths natural s 
