﻿3G BLIND VERTEBRATES AND THEIR EYES. 



THE EYES OF TYPHLOTRITON SPELyEUS STEJNEGER.' 



A single specimen of a salamander was discovered in Rockhouse Cave, Barrie 

 County, Missouri, by Mr. F. A. Sampson in July, 1891. The specimen was 

 described by Dr. Stejneger (Proc. U. S. Nat. Mus., vol. xv, p. 115), as Typhlotriton 

 spekcus. His diagnosis reads as follows : 



Vertebrae opistoccelous ; parasphenoid teeth; vomerine teeth; eyes concealed under the con- 

 tinuous skin of the head; tongue attached in front and along the median line, free laterally and 

 posteriorly; maxillar and mandibular teeth small and numerous; vomerine teeth in 2 strongly 

 curved series; parasphenoid patches separate; nostrils very small; toes 5; 16 costal grooves, 

 or 18 if counting the axillary and groin grooves; tail slightly compressed, not finned; toes nearly 

 half-webbed; vomerine teeth in two V-shaped series with the curvatures directed forward; gular 

 fold strong, very concave anteriorly; color uniformly pale. 



He further wrote, before he discovered Typhlomolgc in the underground streams 

 of Texas : 



Although many of our salamanders are known to inhabit caves, this seems to be the only 

 one, so far discovered, which, like some of the other animals exclusively living in caves, has become 

 blind or nearly so. 



A preliminary note by Eigenmann and Denny (Proc. Ind. Acad. Sci. for 1898, 

 p. 252, 1899) completes the list of papers dealing with this species. 



In the spring of 1897, I visited Rockhouse Cave and secured a number of 

 larvae, which Dr. Stejneger pronounced the larvit of Typhlotriton. Tater Mr. 

 E. A. Schultze informed me that he had seen this salamander in the underground 

 passage leading to Blondi's Throne Room in Marble Cave, Stone County, 

 Missouri. In September of 1898, I visited this cave and secured 4 adults and 

 3 larvae of Typhlotriton. A large number of the larvae were obtained from Rock- 

 house Cave a few days later. Those from the latter cave were found under loose 

 stones and gravel in the rivulet at the mouth of the cave. They had been exposed 

 to the light. It is scarcely supposable that those from Marble Cave had ever 

 been subjected to light. In the caves both larva; and adults are found under 

 stones, the old ones in and out of the water. Occasionally one is seen lying on the 

 bottom of a pool. 



In the aquarium the larvie creep into or under anything available ; a glass tube 

 serves as a "hiding" place. The rubber tube admitting water to the aquarium is 

 sometimes occupied by several during a temporary cessation of the flow of water. 

 A wire screen sloj)ing from the bottom of the aquarium formed the most popular 

 collecting place for the larvie. They collected beneath this, though it offered no 

 protection from the light. From these observations it seems probable that stereo- 

 tropism rather than negative heliotropism accounts for the presence of this species 

 in the caves, and that this reaction has been retained after the long stay of the 

 species in caves necessary to account for the changes in its eyes. 



The eyes of the larvae when examined from the surface appear perfectly normal, 

 but they are little used in distinguishing objects. When hungry they will strike 

 at a stick held in the hand as they would at food. A stick lying undisturbed at 

 the bottom of the aquarium is not molested. They strike at a worm when 

 touched by it, or when it approaches close enough for its motion to be perceived. 



' By Carl H. Eigenmann and Winfield Augustus Ucnny. See Biol. Bull. II. p. 33, iQoo. 



