Anatomy of the Kingfishers. 107 



present an interesting series of modifications in Kingfishers, 

 and in these the scale of specialization dips markedly towards 

 the eutaxic forms. 



Deltuides major. — There can be no donbt but that among 

 birds generally this muscle tends to increase in length, its 

 insprtion extending gradually down the humerus. In Dacelo 

 it has reached halfway down the humerus, and in the other 

 diastataxic forms it has a nearly similar extension, sometimes 

 falling short and sometimes just surpassing that length. In 

 all the eutaxic forms it reaches down beyond the first half, 

 although this downward extension always falls short of that 

 attained in most Pigeons. 



Deltoides 7ninor. — This is in two portions, separated by 

 the tendon of the supracoracoideus, and does not show any 

 striking divergences in the different forms. 



Deltoides proputagialis. — Many writers have made con- 

 tributions to our knowledge of this distinctively Avian 

 muscle, and Fiirbringer in particular has classified the series 

 of modifications which it presents. At one end of the series 

 is the condition in which the muscle lias a single belly, 

 giving off at the distal end the longus and brevis tendons. 

 This condition, obviously more primitive, occurs in most 

 Avian families, and in all but a few exceptional cases among 

 swimming and wading birds. In the next stage the distal 

 extremity gives rise to two muscular peaks, one for the 

 brevis and another, usually smaller, for the longus teudon. 

 This condition occurs in a small number of genera scattered 

 irregularly through the families. In further stages the 

 peaks deepen, the division extending towards the oiigin of 

 the muscle, such stages being of rarer occurrence. The 

 culmination of the series has been attained in Passeres and 

 in a few genera of other birds, in which the original muscle 

 has been divided into a specialized and separate muscle for 

 each tendon. In all the diastataxic Kingfishers the peaked 

 stage has been reached. In Dacelo (Plate IV. fig. 1), in 

 Ceryle maxima (I'late IV. fig. 2) and C. alcyon (Plite IV. 

 fig. 3), and in all tiie species of Sauroputis (Plate IV. fig. 4) 

 the longus peak is smaller than that for the brevis. Among 



