No. 543] SHORTER ARTICLES AND DISCUSSION 159 



Cuba, measuring in total length but 57 mm. 3 Several other hum- 

 ming birds, notably Mellisuga minima (65 mm.) of Jamaica, are 

 but slightly larger. The Trochilidae comprise about 600 known 

 forms, most of which are excessively small. Patagona gigas of 

 the higher Andes, the largest of the group measures about 215 

 mm. in length. The size of the members of this family is an 

 adaptation to the physical requirements of a highly active life, 

 which is essentially that of securing food while hovering before 

 blossoms. The Nectariniida? or sun-birds of the Ethiopian and 

 Indian Regions parallel the Trochilidae in size and brilliancy. 

 The Dieaeidas or " Flower-peckers " of India and Australia, and 

 the Troglodytidaa and Regulida?, wrens and kinglets of this 

 country, likewise contain very small forms. 



Sphccrodactylus sputator Gray (45 mm. plus), occurring in 

 the West Indies, is one of the very smallest of American rep- 

 tiles. 4 8. notatus Baird (50 mm.) of Florida and the West Indies 

 and a number of other West Indian lizards are hardly larger. 

 The largest of existing lizards are members of the Varanidae of 

 Africa, Asia and Australia, the Malayan Varanus salvator 

 (Gray) reaches a length of eight feet. Of the adaptive radia- 

 tions which the Lacertilians have undergone, that branch con- 

 taining the Amphisbaenidae, minute, legless, burrowing forms of 

 tropical America and Africa, is of peculiar interest. This family 

 presents a most remarkable illustration of the principle of 

 heterology of Cope, of parallelism and convergence of other 

 authors. Through the dominance of essentially similar environ- 

 mental factors, certain species have come to resemble the earth- 

 worm with such fidelity, that the very chickens which follow 

 the plow are said to seem unable to differentiate and indiscrim- 

 inately pick them up. 5 



These remarks may apply equally well to the TyphlopidaB 

 and Glauconiidae, still widely distributed in tropical countries, 

 archaic and degenerate, sightless, burrowing snakes, relicts of a 

 once cosmopolitan assemblage, which contain the very smallest 

 known Ophidians. Helminthophis petersi Boulenger (110 mm.) 

 of Ecuador, Typhlops anchietce Bocage (119 mm.) of Angola, 

 Africa, Olauconia dissimilis (Bocage) (104 mm.) of the White 

 Nile and Olauconia bilineata (Schlegel) (110 mm.) of the West 

 'Ridgway, Sep. V. S. Nat. Mus., 1890, p. 295 (1892). 



4 Boulenger, "Cat. Lizards Brit. Mus.," 2d ed., Vol. 1, p. 219, 1885. 



5 Eigenmann, Biol. Bull, Vol. 8, no. 2, p. 60, 1905. 



