116 Mr. P. C. Mitchell on the 



middle head of the gastrocnemius. This condition is typical 

 in Kingfishers and is common in birds. It occurs in Dacelo, 

 Ceryle maxima, four species of Sauropatis, the Halcyunes, 

 Cittura, Ceyx, Alcedo asiatlca, and A. bevyalensis. On the 

 other haud^ in Ceryle alcyon, a diastataxic form, in C. ameri- 

 cana, C. inda (fig. 14, add.), and Alcedo ispida, while the 

 internus is similar, the externvs is either so small as to be 

 practically indistinguishable (Alcedo) or has lost separate 

 identity. 



Popliteus consists in all of a few fibres nearly transversely 

 arranged between the heads of the tibia and fibula. 



Tibialis anticus in all has the usual fleshy head, from the 

 tibial crest and tendinous head from tlie external condyle of 

 the femur. It parses under a fibrous transverse bridge, and 

 is inserted by a single tendon. 



Extensor diyitorum communis in Dacelo arises in the 

 normal fashion under the tibialis anticus; it is inserted to 

 the three digits by three distinct slips. In all the King- 

 fishers it is similar, except that in Ceyx the slip to the index 

 is absent. 



Peroneus superficialis. — Thismuscle is plainly degenerating, 

 possibly in association Avith the degeneration of the fibula, 

 and it is notable that it is quite absent in many of the Pico- 

 Passerine group [Beddard). In Dacelo it arises from the 

 external corner of the tibial crest as a narrow tendon, 

 instead of the more normal broad origin by muscle or 

 fasciae. It is joined by a few fibres from the tibia along the 

 region of the fibula, and is inserted to the kiiee-caj)sule 

 without the usual slip to the flexor of the middle digit. The 

 same conditions exist in all the diastataxic forms and in 

 some of the eutaxic forms. But in other eutaxic forms, 

 notably Ceryle americana and C. inda, in the Halcyones, and 

 Ceyx, it is still more reduced, being simply a long round 

 tendon with the merest vestige of muscular fibres in it. 



Peroneus profundus. — This muscle is relatively better 

 developed, arising from the area of the tibia usually covered 

 by the lower end of the fibula. This is the general con- 

 dition, and suggests an increased strength in compensation 



