ON THE BATRACHIA AND REPTILIA OF COSTA RICA. 



127 









M. 



Length to ear .......... .045 



" to orbit . . . 







. .016 



" of helmet .... 







. .060 



" of dorsal crest (vertical) . 







. .045 



Width between eyebrows 







. .021 



Length of fore limb .... 







. .087 



" of fore foot .... 







. .040 



" of hind limb .... 







. .175 



" of hind foot .... 







. .082 



of tibia 







. .057 



Four of the specimens were taken at Sipurio. 



Having had, through the attention of Professor A. Auguste Dumeril, the oppor- 

 tunity of consulting the types preserved in the museum of the Jardin des Plantes, 

 Paris, I can compai'e the present species with the original specimen of Seba, the 

 type of the B. mitratus of Daudin. In that species, the anterior plume-shaped 

 process of the front is wanting, and the helmet has a more posterior position. 

 There is but one row of scales separating the superciliaries. There are five blackish 

 transverse spots at the base of the dorsal crest, and two longitudinal pale stripes 

 on the head and neck. These characters are borne out by two specimens procured 

 by the expedition under Lieut. Michler from the Isthmus of Darien,* which offer 

 other peculiarities also. Thus the caudal crest is chiefly covered by three longi- 

 tudinal rows of large scales, there being but two or three of small ones below 

 them. M. Bocourt (Miss. Sci. de Mexique, p. 127) states that the rays of the 

 dorsal crest of the B. mitratus are 17-8, and of the caudal, 23; in the B. plumi- 

 frons they are constantly 15-15. The name of the species refers to the plume- 

 shaped process in front of the helmet, which is constantly present. In the female 

 the crests are wanting, and the helmet is very small, posterior, and without plume. 



Mr. Gabb states that this species, like the other Basilisci, haunts the shores of 

 rivers, where it lies on the bases of the leaves of the large canes which fringe the 

 water. Its green color protects it from observation in this position, and it remains 

 motionless when approached, so as to be readily caught by a noose of thread or 

 hair. 



64. Sceloporus malachiticus, Cope, Proceed. Academy Philada., 1864, p. 178. 

 San Jose; Dr. Van Patten, C. N. Riotte. 



* Vid. Proceed. Academy Philada., 1862, p. 356. 



