MUSEUM OF COMPARATIVE ZOOLOGY. 27/ 



hidden. Eustachian tubes not apparent. No vocal sac. Tongue broader 

 forward, free posteriorly. Vomerine teeth, generally present, in two very 

 small groups between the inner nares. Internal nostrils large, anterior 

 very small. Color varying in different individuals from uniform olive brown 

 to brown irregularly spotted with white or so thickly sown with white dots 

 as to appear gray. 



Average length of body about three inches. Two very large specimens 

 were secured; the bodies of these measure a little more than four inches, from 

 snout to anus. One of them is smooth, as is usual ; the other lias numerous 

 prominent nipple-like warts on the flanks from the tympanum backward. 



The young of this species and those of marmoratus are very similar. The 

 adult, however, instead of being erect and trim with prominent palmar and 

 plantar tubercles as the latter, is much depressed and flattened, and carries 

 itself more like Pipa ; it has a great baggy skin which hangs in loose folds 

 about it and the tubercles are slightly developed or absent. 



The vomerine teeth are reduced to a minimum ; often they are absent on 

 one side or altogether. 



As might be expected from the exclusively aquatic habits of culeus, its 

 skeleton is weaker and less perfectly ossified than that of marmoratus. In 

 the latter the skull and its processes are strong and the foramina and fonta- 

 nel very small ; in the other the skull is thin and shell-like, the processes are 

 more slender and the foramina and fontanel larger. Large specimens of 

 culeus are here compared with much smaller ones of the other species. 



These animals are very abundant in the extensive beds of weeds which 

 occur on the bottom of Lake Titicaca. They feed on the molluscs, Crus- 

 tacea, worms, etc., and are fed upon by the birds and fishes. Marmoratus 

 was found in little creeks and marshy places, in situations indicating habits 

 similar to the common Ranse ; during the two months of the observations 

 culeus was only to be found in the lake, crawling lazily about among the 

 weeds or half hidden by them, watching for prey. The latter was the only 

 one found in this vicinity ; the former was secured on the summit and the 

 western slope. These animals are able to remain under water for great 

 lengths of time without coming up for air ; hours of watching in clear 

 water, where many could be seen, failed to detect any approaching the sur- 

 face. It is possible they are more lively at night, when their enemies are 

 less active. Numbers were brought up in the trawl at more than four 

 miles from the shore. None were found on the land. The natives were 

 positive they never left the water. All stages of the animal are represented 

 by the specimens in the collection. On PL I. are given figures from above 

 and in profile (natural size). 



Pleurodema Bibroni Tschudi. 



Abundant at Puno, on the lake. Colors varying. 



