18 
NORTH AMERICAN BATRACHIA AND REPTILIA. 
Order FIRMISTERNIA. 
Family EHGYSTOMIDH]. 
Genus Engystoma, Fitzinger. 
Ethmoid arch ossified; prefrontals in contact with each 
other, and with the completely ossified fronto-parietals ; terminal 
phalanges simple ; ear fully developed ; head small, not distinct 
from body ; tympanic membrane concealed ; toes free on slightly 
palmate ; metatarsi with small tubercles. 
48. E carolinense, Holb. Head short, pointed; body 
thick, nearly oval ; skin smooth ; toes unwebbed ; above chestnut, 
darker along vertebral line; below grayish, thickly sprinkled 
with black specks ; L. one inch. Austroriparian region. 
Order ARCIFERA. 
Family HYLIDHS. 
Ho postorbital process to fronto-parietals, which embrace a 
large fontanelle; xiphisternum deeply emarginate; pupil hori- 
zontal ; vomerine teeth present ; true pollex a simple metacarpal, 
without phalanges. 
A. Digital dilations small. 
a. Toes broadly webbed; tongue extensively free, 
deeply notched behind Acris. 
b. Toes free; superior plate of ethmoid osseous; pre- 
frontals separate Chorophitus. 
B. Digital dilations well developed; tongue completely 
attached or one-third free; posterior digits webbed; vomerine 
teeth in transverse or posteriorly convergent fasciculi Hyla. 
Genus Acris, D. et B. 
49. A. gryllus , subsp. gryllus , LeConte. Head elongated ; 
snout pointed; tympanum rather indistinct; hind legs very long; 
inner and hind part of thighs reticulated ; body above, brownish 
or cinereous ; middle of head and back green or reddish-brown ; 
a triangular dark patch between eyes ; a white line from orbit to 
arm; two or three large oblique dark patches, usually margined 
with white on sides; these markings sometimes wanting; beneath 
white, often varied with dusky; chin and throat tinged with 
yellowish;- L. one and one-half inches. Austroriparian region. 
50. A. gryllus , subsp. crepitans , Bd. Head rather obtuse ; 
inferior surface of thigh plain; general appearance of the pre- 
