AVES LARID^E. 1 97 



that the length of the primary feathers was quite necessary in order to 

 keep their wings dry. When thus employed, their forms resembled the 

 symbol, by which many artists represent marine birds. The tail is much 

 used in steering their irregular course. 



"These birds are common far inland, along the course of the Rio Parana ; 

 and it is said they remain there during the whole year and that they breed 

 in the marshes. During the day they rest in flocks on the grassy plains, 

 at some distance from the water. Being at anchor in a small vessel, in 

 one of the deep creeks between the islands in the Parana, as the evening 

 drew to a close, one of these scissor-beaks suddenly appeared. The 

 water was quite, still and many little fish were rising. The bird continued 

 for a long time to skim the surface ; flying in its wild and irregular manner 

 up and down the narrow canal, now dark with the growing night and the 

 shadows of the overhanging trees. At Monte Video, I observed that large 

 flocks remained during the day on the mud banks, at the head of the 

 harbour; in the same manner as those which I observed on the grassy 

 plains near the Parana. Every evening they took flight in a straight line 

 seaward. From these facts I suspect that the Rhyncops frequently fishes 

 by night, at which time many of the lower animals come more abundantly 

 to the surface than during the day. I was led by these facts to speculate 

 on the possibility of the bill of the Rhyncops, which is so pliable, being a 

 delicate organ of touch. But Mr. Owen, who was kind enough to examine 

 the head of one, which I brought home in spirits, writes to me (August 7, 

 1837,) that 



"'The result of the dissection of the head of the Rhyncops, compara- 

 tively with that of the head of the duck, is not what you anticipated. 

 The facial, or sensitive branches of the fifth pair of nerves, are very small ; 

 the third division in particular, is filamentary, and I have not been able to 

 trace it beyond the soft integument at the angles of the mouth. After 

 removing with care, the thin horny covering of the beak, I cannot perceive 

 any trace of those nervous expansions which are so remarkable in the 

 lamelli-rostral aquatic birds; and which in them supply the tooth-like 

 process, and soft marginal covering of the mandibles. Nevertheless, 

 when we remember how sensitive a hair is, through the nerve situated at 

 its base, though without any in its substance, it would not be safe to deny 

 altogether, a sensitive faculty in the beak of the Rhyncops.' ' 



Punta Arenas. "Later in the day a few of us spent some time on 



