76 BULLETIN 160, UNITED STATES NATIONAL MUSEUM 



those in which development is indirect, Engystomops makes floating, 

 foamy nests for the eggs, while Leptodadylus forms froth nests in 

 contact with water. Although no observations have been published 

 on the life histories of the Mexican species of Eleutherodactylus, it 

 is quite likely that some of the species have the direct development in 

 which the young hatch full}^ formed from the egg capsules. The life 

 histories of Tomodactylus and of the Mexican species of Syrrhophus 

 have not been observed. 



KEY TO GENERA OF MEXICAN LEPTODACTYLIDAE 



1. Vomerine and maxillary teeth present 3 



Vomerine teeth absent 2 



2. Maxillary teeth low, projecting very little if at all bej^ond outer 



ridge of this bone, and often barely penetrating the gum 5 



Maxillary teeth absent; a diamond-shaped area inclosed by 

 glandular dermal ridges, with black outer border and brown, 

 orange, or vermilion-colored center in interscapular region; 

 omosternum cartilaginous, with terminal dilation; 

 mesosternum ossified, forming a straplike bony style, 

 which is bifurcated distally but not proximally, and 

 each of the branches is furnished with a separate car- 

 tilaginous plate (xiphisternum) ; sacral diapophyses 

 moderately dilated; skin of upperparts decidedly 

 tubercular and glandular; tympanum minute or hid- 

 FiGURE 17— ^^^ ^y tubercles; a conical tubercle on middle of inner 

 The T-shaped edge of tarsus; fingers free; toes nearly free; ends of 

 terminal j3ha- fingers and toes slightly swollen, no distinct terminal 

 disks; outer metatarsals united; terminal phalanges 

 with peculiar nodular extremity and rarely with 

 pseudo-T-shaped distal end Engystomops (p. 77) 



3. Mesosternum ossified, forming a bony style; fingers and toes free, 



without distinct distal dila,tions or disks; male of Leptodactylns 

 melanonotus with two spine-bearing tubercles on inner side of 

 first finger; outer metatarsals united; tympanum distinct; 



pupil horizontal Leptodactylus (p. 81) 



Mesosternum not forming a bony style, but cartilaginous, with 



bisagittate (double arrow-shaped) extremity or xiphisternum 4 



4. An external tj^mpanum, more or less distinctly outlined; fingers 



free; toes either free or slightly webbed; terminal phalanges 

 T-shaped (fig. 17); digital dilations or disks present, although 

 generally small, and rarely as large as tympanum; outer meta- 

 tarsals united; pupil horizontal Eleutherodactylus (p. 90) 



No external indication of a tj-mpanvmi; fingers with or without 

 vestige of web at base; toes nearly fully webbed; terminal 

 phalanges T-shaped; apical disks of fingers and toes well 

 developed; body stout; hind limbs rather short; male of 

 Cawphias guatemalensis with well-developed clawlike vestige 

 of pollex buried in fleshy apophysis on side of first finger. Cauphias (p. 118) 



5. Large lumbar gland present, barely visible above the skin, its 



position marked by an irregular dark brown or black area, 

 with two or three white spots, or with white vermiculations; 

 outer metatarsals united; fingers and toes free, with small 

 distally truncated dilations or disks; terminal phalanges 



lanx of FAeu- 

 therodaclylus 



