168 DR. B. C. A. WIU^DLE AKD MP. F. G. PARSOyS OJf THE [Mar. 1, 



metatarsal. Toung and Eobinson (XIY.) state that in the Fox 

 and Dog the peroneus longus is inserted into the cuboid and the 

 4th and 5th metatarsals. We have examined the insertion very 

 carefully in two Dogs (39, 40), and find that, though the sheath of 

 the tendon is attached to these parts, the tendon itself is continued 

 across the sole, not to the base of the second metatarsal bone, but 

 to that of the rudimentary first. 



Peroneus brevis. — This is always present in Carniyora, and rises 

 from the shaft of the fibula below the origin of the peroneus longus. 

 The tendon of insertion, which is large, runs in a groove behind 

 the external malleolus which it shares with the peroneus quinti 

 digiti. It is inserted into the base of the fifth metatarsal boue. 



Peroneus quinii digiti. — This is also very constant, although 

 some authors have described it as a slip from the tendon of the 

 peroneus brevis. The muscular belly is very small and easily 

 overlooked ; it rises from the upper third or so of the shaft of the 

 fibula, and the delicate tendon passes down in the same groove as 

 that of the peroneus brevis, behind the external malleolus. After 

 reaching the dorsum of the foot, it fuses with the tendon of the 

 extensor longus digitorum to the fifth toe (see fig. 3). 



The Peroneus quarti digiti is never found in the Carnivora. 



Gastrocnemius. — This muscle usually consists of two heads 

 rising from above the two condyles of the femur, though in some 

 cases a third or median head can be separated from the external. 

 In the outer and inner heads fabellae may be developed, the 

 external one being the more constant ; and \^e have some reason to 

 believe that the ossification of the internal fabella depends on the 

 age of its possessor. The two fleshy bellies unite below the 

 middle of the leg to form the greater part of the tendo Achillis, 

 the fibres of which are t\^"isted in the manner already pointed out 

 by one of us ^ Among the Felidae, Macalister noticed the presence 

 of a median head in Feh's h-o (1), and Mivart describes four heads 

 to the gastrocnemius of FeJis catus (9). In Fdi» tigris (4), Felis 

 pardus (5, 6), and Felis 'pardalis (8), no median head could be 

 distinguished. Among the Viverridse only two heads have been 

 recorded. There is always a fabella in the outer head, but in two 

 specimens of Cr i^iptoiirocta one (13) had an internal fabella and 

 the other (14) had not. In two specimens of Viverrci (16, 17) the 

 same thing was observed. 



In the Canidse, fabellae were found in both heads in Canis fami- 

 linris (39), Canis aureus (50 ff), and Canis mesomelas (51). 



In the Ursidos, Kelley (XXIV.) points out that the gastrocnemius 

 is much smaller in proportion in the Polar Bear than in the Cat. 

 Shepherd (XX.) says that " in Ursus arnericanus (59) the three 

 heads," one of which is evidently the plantai-is, "remain distinct 

 as far as their insertion." In Cuvier and Laurillard's specimen of 

 the same animal (62) the two heads unite quite low down in the 

 leg. The Procyonid^ serve very well to show the inconstancy of 



' " Oil the Morphology of the Tendo Achillis," by F. G. Parsons. Jouni. 

 Auat. Tol. xxviii. p. 414. 



