Rudimentary Hallux of the Kittiwake. 



445 



occupies a small area, and is placed two or three times its 

 own length from the tip of the digit. It has not the appear- 

 ance of a claw, for it does not project beyond the general 

 surf ace, only presenting a slightly raised central portion, which 

 represents the tip of the nail. This nail is very thin when 

 compared with the corresponding structures on the other 

 digits of the specimen. The possession by the digit of a 

 flexor lungus haUucis is indicated by the presence of the 

 tendon shown in fig. 2, which gives details of the hallux of 

 this specimen as seen in section. 



Fig. 2. 



C.T. 



Section (diagrammatic) of haUux of ripe embryo of Rissa tridactyla. x 70. 



N, nail ; N.B., nail-bed ; P.P., proximal phalanx ; D.P., distal phalanx ; 

 T, tendon ; M.T., tarso-metatarsus ; E, epidermis ; C.T., connective 

 tissue. 



The phalanges of all these embryonic specimens were, of 

 course, more or less cartilaginous, but it is notable that 

 when compared with those of the other digits, of the same 

 specimen, the phalanges of the hallux were uniformly less 



