120 MR. A. H. GARROD ON THE MUSCLES OF BIRDS. [Feb. 3, 



the Psittaci (which in other points also are peculiar), and the Cucu- 

 UncB from amongst the Cuculidae, they all possess the accessory 

 femoro-caudal (B) well developed. The semitendinosus (X) and 

 the accessory semitendinosus (Y) are always present, and, except in 

 Casuarius, Drotnceus, aud some Psittaci, the ambiens is to be found 

 well developed. 



The presence of both the accessory femoro-caudal and the acces- 

 sory semitendinosus (that is, of both B and Y in their myological 

 formula) is the most characteristic feature which they have in 

 common, giving the formula B. X Y as typical. 



The Anseriformes include most of the web-footed birds. Their 

 most marked characteristic is the presence of the accessory femoro- 

 caudal (except in Bulweria), whilst the accessory semitendinosus is 

 absent, except in the Storm-petrels. With the exception of the Podi- 

 cipidce, the femoro-caudal is present ; so that their formula is nearly 

 always A B. X. Excluding Podiceps and a Storm-petrel in the case 

 of one specimen examined, I have always found the ambiens present. 



The Ciconiiformes are less easily defined than the other groups. 

 The caeca coli are never long ; the accessory femoro-caudal is never 

 present ; and the obturator externus is frequently more developed 

 than in other birds, to replace it in action. It is in the pectoral 

 region that these birds most closed agree. The strong short anterior 

 costo-coracoid ligament, the bowed space between the superior 

 margin of the second pectoral muscle and the furcula, and the fre- 

 quently complicated arrangement of the great pectoral, whereby it is 

 developed in a superficial and a deep layer (in which, by the way, 

 the Procellariidce agree with then,), all point to a not far distant 

 relationship. The Ardeidce are the most aberrant of the order, the 

 ambiens muscle being always absent in them at the same time that 

 there is only one colic caecum. 



The Charadriiformes correspond to the Schizorhinae, so named by 

 me on account of a peculiarity in the structure of the nasal bones, 

 which is sufficiently special in my estimation to justify the separation 

 of all those birds in which it ^is found into a single order by 

 themselves. There are considerable myological differences amongst 

 its families according to their habits, the only uniform character 

 being the presence of the femoro-caudal muscle. The ambiens is 

 absent in the Alcidce (A/ca, Uria) and some Columbce. 



The minor divisions of the orders above defined must now engage 

 our attention. 



The order Galliformes may be divided into three main divisions 

 or cohorts — a. the Struthiones, jo. the Galiinacece, and 7. the Psittaci. 



u. The Struthiones are peculiar in the structure of the palate ; 

 and in them the sciatic nerve and artery always perforate the fibres of 

 the accessory femoro-caudal in a manner not found in any other birds. 



They are divisible into four families, the first three of which have 

 no oil-gland : — 



1. Strut hio and Rhea, which form each the type of a separate 

 subfamily. In common they have the formula B. X Y, the ambiens 

 muscle present, and long sacculated caeca coli, which in Struthio are 



