BY T. THOMSON FLYNN, B.Sc.' 185 



to the base of the first phalanx of the hallux, but is per- 

 forated in this position by the tendon of M. flexor longus 

 hallucis. 



The method b}' which the two muscles M. flexor 

 perforans digiti iv. and M. flexor perforatus digiti iv., are 

 made to act on five phalanges is interesting in these 

 birds. The arrangement in M. flexor perforans is simple. 

 It perforates the tendon of M. flexor perforatus, and 

 passes to the ungual phalanx, being inserted into it in 

 two places, at the base of the terminal phalanx, and 

 also a little in advance of this, just at the base of the 

 nail. It gives off also small slips to the penultimate 

 and ante-penultimate phalanges of this digit. 



The perforated flexor, of course, becomes divided 

 into two parts — an inner and an outer. The inner of 

 these passes to be in&erted into the base of the fourth 

 phalanx, giving off atso a slip to the third. The outer 

 slip divides almost immediately into two, of which one 

 becomes inserted into the base of the third phalanx, 

 while the other divides again into two, one part being 

 inserted into the base of the first phalanx, the other into 

 the base of the second. 



M. adductor digiti iv. About this muscle Gadow 

 (Bronn's Thier-reichs, Aves, p. 204-5), says : — " Diesen 

 Muskel, der nicht in der Literatur erwahnt ist habe ich 

 nur bei sehr wenigen Vogeln gefunden : Bei Rhea 

 (nicht bei den ubrigen Ratiten gesehen) entspringt er 

 als ein sehr dunner Muskel fibular neben dem M. ab- 

 ductor dig. ii. und ist theilweise mit dem ihn lateral 

 begrenzenden M. abductor dig. iv. verwachsen. Seine 

 Sehne geht durch das Spatium intertarsale externum zur 

 Tibialseite der Basis phal. i. und adducirt die Aussen- 

 zelie neben geringer Plantarflexion. Bei Bucorvus ent- 

 sprang er von distalen Ende der Tarsus : bei Rhampas- 

 tus war er noch kurzer und nutzlos." 



In the Megapodes, it arises from the upper part of 

 the anterior aspect of the tarso-metartarse, and from 

 part of that bone as well as from the side of the extensor 

 brevis digitorum. It is a thin spindle-shaped muscle, 

 which develops a thin rounded tendon passing down- 



