402 



REPTILIA— ORDER IIL—SQUAMATA. 



expansion of skin runs from the nape of tlie neck to the loins, where it is 

 separated bj' a short interval from the one on the tail. In the back the 

 crest is supported by the elongation of the spines of the back-bone; and in some 

 cases the expansion on the tail is strengthened in a similar manner. The 

 males have in addition a helmet-like elevation on the hinder part of the head. 

 Basilisks are tree-dwelling reptiles, nearly always found in the neighbour- 

 hood of water. They generally repose on a bough overhanging some pool or 

 river ; and when frightened, immediately throw themselves into the water, in 

 which the males swim with facility by the aid of the crested tail, which acts 

 as a rudder. How the female manages to get along without the crest is not 

 stated. 



From a group so extensive as that of the iguanas it is difficult to select the 

 forms best deserving of special notice. There is, however, no doubt that 

 two curious lizards from the Galapagos Islands demand recognition here. Each 

 of these is the sole representative of a genus by itself ; but whereas one 

 {Amblyrhynchus cristaius) lives to a great extent in the sea and feeds on sea- 

 weed, the other {Gonoloplius subcristatus) is a terrestrial creature subsisting 

 on a more ordinary vegetable diet. Having pores on the thighs, and the 



fourth toe of the hind-foot longer 

 than the third, these lizards are 

 specially distinguished by the cir- 

 cumstance that both the front and 

 lateral teeth are three cusped. The 

 marine species, which measures over 

 fifty inches in length, and is con- 

 siderably the larger of the two, 

 takes its scientific name from the 

 extreme shortness and bluntness of 

 the head ; both the body and tail 

 being markedly compressed, and 

 the toes furnished with incipient 

 webs. The upper surface of the 

 head is ornamented with a number 

 of conical bosses ; and a strong ser- 

 rated crest runs from the nape of 

 the neck to the tip of the tail. The habits of these remarkable lizards have 

 been well described by Darwin. He states that these reptiles are seldom found 

 farther inland than a few yards distance from the shore ; and that when in 

 the water they swim strongly and easily with a serpentine movement by the 

 aid of the powerful tail alone. On the volcanic rocks forming the coasts of 

 their native islands these lizards are met with in large droves, which from 

 time to time proceed to sea in search of food. In spite, however, of this 

 fondness for the sea, they never take to the water when attacked as a means 

 of escape. The smaller terrestrial species is easily distinguished by the 

 cylindrical form of the tail and the absence of any trace of webbing on the 

 toes. The head, too, is somewhat longer, and the dorsal crest fully developed 

 only in the region of the neck. In weight, they scale from ten to fifteen 

 pounds. On the central islands of the Galapagos group these lizards are, or 

 were, found in such numbers that there is sometimes a difficulty in discover- 

 ing a space of any size free from thorn. They live in burrows, and in the 

 daytime love to lie basking in the sun for hours at a stretch in a dull, listless 

 manner. Even when disturbed, they are slow to get out of the way ; and in 



Fiif. 15. — Galapagos Sea-Ltzard. 

 {Ainblyrhyiidius cristatus). 



