I20 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



comes nearer to Pyocellaria pelagica than to any other species ; and it is 

 probably congeneric wWi it, though it differs somewhat^ in the proportion 

 of the tarsus and toes, and very widely in its patte'rn of coloration. The 

 proportions of the tibia and tarsus differ from those of pehigica in the 

 greater comparative length of the former.' 



"Amongst the Petrels mentioned at various times by the late Prof Gar- 

 rod as having been examined by him, a species several times occurs which 

 is doubtfully named ' Procellaria (or Thalassidvojiia) fregataf The 

 specimens dissected by him are now before me, and have been identified 

 by Mr. Salvin as being really referable to the Procellaria nereis of Gould, 

 an example of which, from the Falkland Islands, is now in the museum 

 of Messrs. Salvin and Godman. A careful examination of the three spirit- 

 specimens of this bird, as well as of the skin mentioned, have convinced 

 me that this species is not referable to the true genus ProceUaria as repre- 

 sented by ProceUaria pehigica, and is in fact in no way related to that 

 group of Petrels, but has its nearest allies in the flat-clawed genera Ocean- 

 ites, Fregetta, and Pehigodronia. 



"In his paper on the muscles of the thigh in Birds ^ the late Prof Garrod 

 divided the Nasutae, or Petrels, into two groups, the 'Storm Petrels' and 

 the Fulmaridas, the former group differing from the latter in that they 

 possess the accessory semitendinosus muscle (Y), but lack intestinal caeca. 

 In the Fulmaridae, on the other hand, the accessory semitendinosus 

 muscle is absent, but caeca are present. The species of Storm Petrels on 

 which this generalization was based are called, with doubt, ' Procellaria 

 pelagica and P. fregata,' the latter being the species now identified by 

 Mr. Salvin as P. nereis. As regards the first named species, there can 

 be little or no doubt that the bird really dissected by Prof Garrod, and 

 called by him 'Procellaria pelagica,' was Wilson's Petrel [Occanites 

 oceaniciis), as in this bird there are no caeca, at the same time that the 

 accessory semitendinosus muscle is present. The true Procellaria pela- 

 gica (of which I have lately dissected two perfectly fresh examples) agrees 

 with the Fulmaridae, as defined by Prof Garrod, in having caeca, but no 

 accessory head to the semitendinosus ; and Cyntochorea leucorrhoa agrees 

 in both these points with Procellaria pelagica. 



"The so-called 'Procellaria nereis' of Gould is therefore obviously not 



'"The italics are mine. W. A. F." 

 'P. Z. S. 1874, p. 122. 



