FROGS OF COLOMBIA — COCHRAN AND GOEST 289 



Variation. — Structurally, the greatest variation seems to be in 

 size. The specimens at hand range in head-body length from 19.5 

 millimeters in the smallest male to 24.3 millimeters in the largest 

 female. There is, likewise, a variation in the conspicuousness of the 

 dorsolateral subdermal lymph sacs. In most individuals these sacs 

 are very conspicuous, but in others they are much less so; this may 

 be due to thicker or more heavily pigmented skin rather than to less 

 well-developed sacs. 



While most of the specimens are without pigment on the back, 

 14 of the 41 at hand show some degree of dorsal pigmentation. In 

 four specimens this pigmentation simply amounts to tiny, pencil-like 

 flecks scattered more or less over the back, but USNM 152066, from 

 Florencia, the pigment is arranged in a pattern similar to that in H. 

 phlebodes. It is impossible to judge whether the variation in pattern of 

 this specimen from Florencia is due to simple geographic variation, 

 whether it represents incipient speciation, or, in fact, whether the 

 Florencia population represents a species other than H. mathiassoni. 



The lymph sac showing through the skin of the dorsum surely 

 represents the "very pale lavender stripe from snout to groin" as 

 described by Stebbins and Hendrickson (1959, p. 525). 



Remarks. — To our knowledge, the only published account per- 

 taining to this species is that of Stebbins and Hendrickson (1959) 

 in which four specimens from Villavicencio are compared with H. 

 microcephala from Huila. Stebbins and Hendrickson heard the Villa- 

 vicencio specimens call shortly after dark on November 18, 1950, 

 and at 10:30 a.m. in bright daylight on November 20. They give 

 the following notes on the life history of the Villaviciencio frogs (Steb- 

 bins and Hendrickson, 1959, p. 526): 



A pair found in amplexus at Villavicencio was placed in a container in which 

 the female deposited her eggs. These were laid in a fairly compact, rather smooth- 

 surfaced, ovoid mass, measuring 37 mm. in length, 21 mm. in width, and about 

 9 mm. in depth. There were approximately 180 eggs, essentially her total com- 

 plement, since less than a half dozen large ova remained in her oviducts. The 

 ova were about 1 mm. in diameter with the lower quarter cream color and the 

 remainder brown. They were surrounded by a stiff jelly capsule, 1.5 mm. in 

 diameter. Beyond this was a softer jelly that more or less merged with that of 

 adjacent eggs but was set off sharply from the inner capsule. The zones of juncture 

 between the outer capsules were made out with difficulty; there was little tendency 

 for the eggs to separate at these zones. 



21. LEUCOPHYLLATA group 



This group is composed of small frogs, generally conspicuously 

 patterned, that are characterized by having a patagium, thighs 

 nearly or entirely without pigment, and a pair of oval glandular 

 areas on the chest. There are a dozen or more species in this group 



