MUSCULAR SYSTEM 613 



on the dorsal face of the base of the first phalanx of the hallux. 

 Generally best developed in Birds with a large hallux, as Apteryx, 

 Galling Accipitres, Steganopodes and Herodii, but yet very small in 

 Picus and absent in Psittaci. When the hallux is very small, as in 

 Pterodes and many Limicolaz, this muscle still exists, and though 

 slender is rather long. 



Mm. flexores longi digitorum consist of three principal sets, 

 each of which is again divided into several muscles, the hallux 

 having one, the fourth toe two, and the third and second toe three 

 each, which are conveniently distinguished by the relation to one 

 another of their respective tendons. Those that are inserted on 

 the base of the first phalanges are perforated immediately above 

 the insertion by the tendons of those that are inserted on the 

 second and third phalanges, which in their turn are perforated by 

 those that are attached to the terminal phalanges hence there are 

 perforati, perforantes et perforati, and perforantes. 



Mm. flexores perforati digitorum ii. Hi. iv. These three, of which 

 each anterior toe has one, arise in a variable way, either separately 

 or partly blended, from almost any part of the region of the knee, 

 but especially from the posterior intercondylar space of the femur, 

 from its outer condyle, from the ligaments of the knee and patella, 

 the proximal part of the tibia and fibula, and lastly from the 

 tendon of the m. ambiens (page 11), of which in most cases the m. 

 perforatus Hi. partly forms the continuation. Each of them be- 

 comes a distinct tendon which passes posteriorly over the inter- 

 tar sal joint, and piercing the pad above mentioned, runs along the 

 plantar groove of the metatarse to be inserted ventri-laterally on 

 the base of the first phalanx of the second, third or fourth toe as 

 the case may be their insertion being perforated as before stated. 

 The tendon of the m. perforatus Hi. may be easily recognized, first 

 by its passing the intertarsal joint and the pad the most super- 

 ficially, and next by its receiving below that joint the lateral 

 distal tendon of the m. peroneus superfidalis. The tendon of m. 

 perforatus ii. often passes the pad through a special canal, but in 

 Struthio is wholly absent, in conformity with the loss of the corre- 

 sponding toe. The tendon of m. perforatus iv. passes the intertarsal 

 joint as superficially as that of the third toe, and is often inserted 

 on all the four proximal phalanges of the fourth toe. 



Mm. flexores perforantes et perforati digitorum ii. et Hi., with a 

 similar origin to the last group, except as regards the m. ambiens 

 (page 11). The tendon of the second toe pierces the pad by a special 

 canal, and is inserted on the plantar and lateral faces of the base 

 of its first or second phalanx, after having perforated that of the 

 foregoing and being perforated by that of the following muscle. 

 It is absent in Struthio. The tendon of the third toe in many 

 Birds receives a vinculum or slip from that of the m. perforatus Hi., 



