THE ISLANDS OF THE BAY OF BENGAL, 157 



feathered ; whereas in acuticauda the whole of the foot and 

 base of the toes are bare and whitish, and the tarsus is only scan- 

 tily feathered : the difference in the feathering of the feet, as 

 also in their coloration, is very marked. In size I do not think 

 that any great difference exists. Apus adult is about 7*5 

 inches long; acuticauda, adnlt male, 7'25; adult female, 7 - 63 ; 

 apus wing from flexure, 675 to 7 inches ; acuticauda, male, 6*4 

 to 6'6 ; female, 6 - 8. As regards the tail I cannot see that the 

 feathers in acuticauda are perceptibly more acuminate than 

 in apus. 



The lateral tail feathers in the adult female, in both apus 

 and acuticauda, exceed the central by T25 ; in the adult male 

 and younger birds of both sexes of acuticauda the difference 

 is less. In color the adult female acuticauda is scarcely in 

 any respect distinguishable from adult apus from Europe, 

 save and except that the white on the chin and throat is per- 

 haps purer, and of somewhat greater extent. In the young 

 birds there appears to be a somewhat greater difference ; the 

 ■white edgings of the feathers mainly confined in apus, to the 

 best of my belief, to the head, in acuticauda extend to those of the 

 back, breast, rump, upper and lower tail ^ coverts, and wings, 

 and towards the front of the head are so extensive that the 

 lores and forehead appear altogether white. 



I may note that like apus, acuticauda has a barbatus stage, 

 (vide Stray Feathers, 1873, p. 165), in which all the white 

 feathers of the chin and throat are brown shafted. 



The occurrence of this species at the Andamans in July is 

 very remarkable. 



103 bis.— Collocalia linchi, Horsf. (28.) 



I have already made a good many remarks about this species 

 and its congeners, Stray Feathers, 1873, p. 294. I have not 

 yet received, though I hope to get them hereafter, Javan spe- 

 cimens, and I cannot, therefore, sa}^ for certain whether this bird 

 should stand, as I believe, under the above name, or whether 

 the Javan bird is really distinct, and our present should retain 

 my late friend Colonel Ty tier's name qffinis ; but I think it is 

 perfectly clear that Thunberg's fuciphaga is a totally different 

 bird belonging to the same sub-group as Collocalia unicolor, 

 Jerdon, Collocalia innominata, nobis, &c. 



This species breeds abundantly both in the Andamans and 

 Nicobars. 



Normally it breeds in caves, indeed in a manuscript note 

 given me with many others by the late lamented Colonel Tytler, 



