LARID.E — THE GULLS AND TEllNS — HYDKOCHELIDON. 



317 



hi 111" par excellence^ and is more or less confounded with the S. fuUg'mosa. Mr. Law- 

 iviice, in his jjaper on the Birds of Sombrero — a rocky islet near St. Martin's — 

 ([notes Mr. Julien as believing that the number of individuals of this species which 

 visited that place was at one time equalled only by those of S. maxima and Anons 

 sfolldKs. It is said to be remarkable for its social peculiarities — almost always asso- 

 ciating with the Noddies ; and in however great numbers it may be present on any 

 I\cy, it is found to be almost always more or less mixed with flocks of that Tern. 

 It arrives at Sondn-ero in March, and departs in August. Its nest is said to be similar 

 to tiuit of the Noddy, and it lays but one egg. It often flies high, and with a pecu- 

 liarly quick darting motion, keeping up a noisy chattering very different from the 

 discordant " caw-caw " of Anous stolidm. Mr. Julieu never observed the two species 

 to quarrel with each other, although individuals of the same species often engaged in 

 long cand obstinate combats. 



The eggs of this bird found at Sombrero are described by Mr. Lawrence as meas- 

 uring 1.88 inches in length by 1.25 in breiulth, as having a ground-color of a creamy 

 wliite, and as being marked with blotches of deep rusty brown, most abundant on the 

 larger end. Eggs collected in British Honduras by Mr. Osbert Salvin vary in length 

 from 1.90 inches to 1.8/5, and in breadth from 1.35 to 1.30. Their ground-color is pale 

 brownish cream, and the markings are small spots of burnt-sienna and lavender-gray. 



Mr. Cory found birds of this species breeding in large numbers at Clarence Harbor. 

 They were in company with the Sooty and the Roseate Tern ; and eggs jjrocured as 

 late <as June 8 were quite fresh. In their breeding habits Mr. Cory found them very 

 similar to the fulifjuinsa. Their eggs were found deposited in sheltered clefts in ledges 

 of locks, or in cavities among the loose bowlders which lined the sea-shore. The egg 

 in all instances was single, and resembled that of the fiiliginom, but was more 

 spotted about the larger end, while the reddish tinge of the ground-color was much 

 fainter. The egg taken by Mr. Cory measures 2.00 inches in length by 1.42 in 

 Incadth ; the ground-color is a rich cream, strongly washed with a rufoiis tint ; 

 around the larger end is a ring of large and confluent blotches of reddish brown ; 

 smaller spots of the same are diffu!-:.'d in a scattered manner over the whole egg, with 

 ohscurc shell-markings of lilac and slate. 



An egg in ...y collection, taken by Mr. Godeffroy on the coast of New Guinea, 

 nicasiires 2 05 inches by 1.45. The ground-color is pure cream, without a tinge of any 

 other shade. Grouped annind the larger end, covering nearly the entire portion, are 

 numerous spots of light brown, and others of much deei)er shade, interspersed, and 

 occasionally confluent. Smaller ones are sparingly scattered over the entire surface, 

 and there are also a few shell-markings of a faint purple. 



GRxrs HYDROCHELIDON, Boib. 



JTi/drndielidon, Hoie, Isis, 1822, 503 (type, Slcma nigra, Linn.). 



( 'hau. Siiniliir to tlio siniiUcr sju'cii's of Sterna, but tnil only very Rliglitly forked or enmrgi- 

 iiiili', iho rectrices not ntti'uuiited at unds, and tho webs of tlic toes filling less than half the inter- 

 (li^'ilid spaces. A<lulta gray or blackish beneath, as dark as, or darker than, the color of the upper 

 siufiicc. 



'i'hc three known si)eiMos of this genus may be defined aa follows — //. leuroparia l)cing included, 

 iwutly for coiuiiarison, but more especially on account of having been obttuncd iu thtj West Indies, 

 ami therefore entitled to a place in the American fauna ;-^ 



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