625 



SYLOCHELIDON. STRONG-BILLED-TERN. 



The genus Sterna of Linnceus is a very natural assem- 

 blage, composed of numerous species, which, if not from any 

 absolute necessity, resulting from strongly-marked diiferences, 

 yet from analogy of similar cases, in which expediency fur- 

 nishes a pretence, if not a reason, may be placed in small 

 groups, to be considered as genera. Some of those proposed 

 by authors are quite incapable of being defined or charac- 

 terized, although they are distinguishable by one who is 

 satisfied with minute differences. The large-billed species 

 form a genus which in reality differs very little from the 

 smaller billed, and which I cannot define better than as 

 follows : — 



Body moderately stout, Avith the neck short ; the head 

 broadly ovate, anteriorly narrowed. Bill nearly straight, 

 tapering, compressed, stout, with the edges sharp, the tips 

 elongated and pointed ; the upper mandible gently arcuate, 

 the lower with the junction of the crura beyond the middle 

 and slightly prominent ; legs short, slender ; anterior toes 

 small ; wings very long and acuminate ; tail forked. 



Being the largest species of their family, with the bill 

 more developed, they have been assumed to be more rapa- 

 cious, and accordingly named : — EuAoj/jprey ; keXiSwi', swallow. 

 One or two compilers write Stylochelidon; and not a few 

 are quite puzzled as to the gender of Chelidon, some making- 

 it neuter, others masculine or feminine. Even the learned 

 Prince of Canino makes Sylochelidon and Gelochelidon 

 feminine, and Hydrochelidon neuter. 



VOL. V. 



