ssessing a frontoparietal fontanelle, in generally having a
maxillary-quadratojugal gap, and in having a free swimming tadpole
stage.

[Illustration: FIG. 5. Outline drawings of _Leptodactylus melanonotus_
(left, KU 65704, x 2) and _Eleutherodactylus alfredi_ (right, KU 93994,
x 2).]

KEY TO MEXICAN LEPTODACTYLID GENERA

1. Small (20-40 mm.), pustular, toadlike frogs;
maxillary and premaxillary bones not bearing teeth _Engystomops_

Large (20-110 mm.), smooth skinned and non-toadlike
frogs; maxillary and premaxillary bones bearing teeth 2

2. No conspicuous waist (Fig. 5); sternum bearing
bony style, _Leptodactylus_

Constrictions at waist (Fig. 5); sternum
cartilaginous, no bony style 3

3. Few (less than six), if any, supernumerary
tubercles on plantar surface _Eleutherodactylus_

Many (more than 8) supernumerary tubercles on
plantar surfaces 4

4. Terminal, transverse groove across tip of
digits, especially outer two fingers, digits
expanded or not; small frogs (18 to 40 mm.) 5

Tips of digits lacking transverse groove;
digits unexpanded; medium-sized to large frogs
(37 to 94 mm.) _Hylactophryne_

5. Lumbo-inguinal gland compact, oval _Tomodactylus_

Lumbo-inguinal or inguinal gland absent or
diffuse and irregular in outline _Syrrhophus_

LITERATURE CITED

DIXON, J. R.

1957. Geographic variation and distribution of the genus
_Tomodactylus_ in Mexico. Texas Jour. Sci., 9:379-409,
December.

DUELLMAN, W. E.

1958. A review of the frogs of the genus Syrrhophus in
western Mexico. Occas. Papers Mus. Zool. Univ.
Michigan, 594:1-15, June 6.

1961. The amphibians and reptiles of Michoacan, Mexico. Univ.
Kansas Publ. Mus. Nat. Hist., 15:1-148, December 20.

FIRSCHEIN, I. L.

1954. Definition of some little understood members of the
leptodactylid genus _Syrrhophus_, with a description
of a new species. Copeia, 1:48-58, February 19.

GALLARDO, J. M.

1965. A proposito de los Leptodactylidae (Amphibia Anura).
Papeis Avulsos, 17:77-87, January 30.

GORHAM, S. W.

196