164 BULLETIN 58, UNITED STATES NATIONAL MUSEUM. 



ARTIFICIAL KEY TO THE FAMILIES OF LIZARDS OCCURRING IN JAPAN AND ADJACENT 



TERRITORY.^ 



a' No large symmetrical shields on top of head. 



6' Digits dilated; no movable eyelids; tympanum exposed Gekkonid^, p. 164 



b' Digits compressed; movable eyelids; tympanum concealed ...Agamid.e, p. 182 



a- Top of head with large symmetrical shields. 



6' Ventral scales cycloid, arranged quincuncially Scincid^, p. 193 



b- Ventral scales squarish, in longitudinal and transverse series. . . Lacertid.e, p. 228 



Family GEKKONID.'E. 



The Geckos are lizards with smooth or papillose tongue, dilateH 

 clavicles and biconcave vertebrae; mostly without movable eyelids 

 and with vertical pupil; toes variously modified or dilated into more 

 or less adhesive organs. 



A large family they are represented in all the hotter portions of the 

 globe, but are most numerous in the Indian and Australian regions. 

 In the area covered by this work only four or five genera have been 

 found. Owing to the ease with which the geckos may be accidentally 

 transported from place to place, they are often introduced uninten- 

 tionally into new localities by human agency. 



Probably most of the species are nocturnal, and owing to the con- 

 struction of the toes are enabled to run with ease on smooth perpen- 

 dicular surfaces. Some species emit a chuckling sound resembhng 

 the word "gecko," hence their name. They lay round eggs with a hard, 

 white shell. 



Swinhoe has given a spirited account of the habits of the common 

 Japanese house gecko as observed by him in Formosa, which deserves 

 to be reproduced here.'' 



In running over the perpendicular face of the wall they keep so close and their 

 movements are made so quickly with one leg in advance of the other that they have 

 the appearance at a distance of gliding rather than running. The tail is somewhat 

 writhed as the body is jerked along, and much so when the animal is alarmed and 

 doing its utmost to escape; but its progress even then is in short runs, stopping at 

 intervals and raising the head to look about it. If a fly perch on the wall it cau- 

 tiously approaches to within a short distance, then suddenly darts forward, and 

 with its quickly protruded glutinous tongue fixes it. Apart from watching its curious 

 maneuvers after its insect food, the attention of the most listless would be attracted 

 by the singular series of loud notes these creatures utter at all hours of the day and 

 night, more especially during cloudy and rainy weather. These notes resemble the 

 syllables "chuck-chuck''' several times repeated, and, from their more frequent 

 occurrence during July and August, are, I think, the call notes of the male to the 

 female. During the greater part of the day the little creature lies quiescent in some 

 cranny among the beams of the roof or in the wall of the house where, however, it is 

 ever watchful for the incautious fly that approaches its den, upon whom it darts forth 



a For nomenclature of head-shields of lizards, see p. 194, figs. 176-178. 

 6 Swinhoe, Ann. Mag. Nat. Hist. (3), XII, 1863, pp. 222-223. 



