18/2.] MR. W. H. HUDSON ON BUENOS-AYREAN SWALLOWS. 605 



roulini are longer, narrow more gradually towards their extremities, 

 and are more arched (see figs. 1 and 2) ; and, secondly, in the much 

 less elevation of the cranial crest in T. roulini, the upper surface of 

 this ridge being continued in nearly the same horizontal plane as 

 that of the nasal bones, instead of forming a considerable angle with 

 it. Besides these points, the fronto-nasal suture was nearly straight 

 in T. roulini, instead of being deflected forwards between the two 

 nasals as in T. americanus, and the deep grooves at each side of the 

 uasal bones were broader in T. roulini than in T. americanus. 



A communication was read from Viscount Walden, F.R.S., Presi- 

 dent of the Society, containing an Appendix to his paper on the Birds 

 of Celebes, read at the meeting held on the 2nd of May, 1871. 



The first portion of this communication contained additional ob- 

 servations upon the species contained in the former list. 



The second portion contained a list of twelve additional species, 

 with remarks upon them, thus raising the total number of authentic- 

 ally recorded Celebean birds to 205. 



This paper will be published in full in the Society's 'Transactions.' 



Prof. Owen read the eighteenth of his series of memoirs on the 

 extinct birds of the genus Dinornis, in which the characters of a sup- 

 posed new species of Dinornis, from the south island of New Zealand, 

 allied to D. crassus, were pointed out, and the species was proposed 

 to be called Dinornis gravis. To this was added a resume of the 

 described species of Dinornis. 



This memoir will be published entire in the Society's 'Transac- 

 tions.' 



Mr. H. E. Dresser exhibited eggs of the Marbled Duck (Quer- 

 auedula marmorata), lately obtained by Major Howard Irby near 

 Seville. 



The following papers were read : — 



1. On the Habits of the Swallows of the Genus Progne* met 

 with in the Argentine Republic. By W. H. Hudson, 

 C.M.Z.S. With Notes by P. L. Sclater. 



[Keceived March 1, 1872.] 



Before leaving Buenos Ayres last summer I had begun to write 

 about our Swallows, and in the present communication will speak of 



* After examining a oonsiderable series of skins of birds of this genus from 

 various parts of America, I have come to the conclusion that there are only four 

 well-marked forms which merit specific rank, namely : — 



1. Progne purpurea (Linn.). 



Under this head I include all the American " Purple Swallows," of which 



