548 ON THE RUDIMENTARY HALLUX OF BIRDS. [June 20, 



Mr. Sclater also exhibited some Lepidopterous and other Insects 

 which had been recently reared at the Insect-House in the Society's 

 Gardens under the care of Mr. A. Thomson. 



The following is a list of the species exhibited : — 



Attacus mylifcta. 



Cynthia. 



Samia cecropia. 



Cricula trifenestrata. 



Deilepbila euphorbiiE. 

 Trochilium apifovme. 

 melauocephaluiu. 



Sciapleron tabaniforme. 

 Sesia scoliiformis. 



■ formiciforinia. 



conopit'ormis. 



musoiformis. 



spheciformis. 



Argyunis papliia. 

 Lycaena iolas. 



Mr. W. A. Forbes exhibited preparations showing the rudimentary 

 hallux of several birds commonly described as three-toed, and made 

 the following remarks : — 



" Whilst engaged in working out my ' Report on the Anatomy of 

 the Petrels ' for the 'Voyage of H.M.S. Challenger,' I happened 

 to come across Dr. Kidder's note ' on the existence of a rudimentary 

 external hallux in Phcebetria fuliyinosa, a bird hitherto supposed, 

 like other Albatrosses, to lack the hind toe altogether. Finding, on 

 an examination of my specimen, his remarks correct, I proceeded to 

 examine examples of three other species of Albatrosses that I had in the 

 flesh, namely I)iomedea exulans, D. brachyura, and Thalassiarche cul- 

 minata. In all of these I discovered a hallux present, though in a most 

 rudimentary condition, consisting of a single small nodule of bone, 

 which lies altogether underneath the skin, in the fibrous subcutaneous 

 tissues, and only appears externally as a minute pimple-like elevation, 

 with no claw. In Phoebetria there is a minute claw visible externally, 

 whilst internally two small bony nodules are discernible, representing 

 undoubtedly the metatarsal element and the hallux, which, as in all 

 other Tubinares, is reduced to a single phalanx. It is difficult at 

 present to say whether the single nodule of the other Albatrosses 

 represents these two elements fused together, or only one of them : 

 in the latter case it is probably the phalanx itself that is wanting^. 



" The discovery of the rudimentary hallux in the Diomedeinse has 

 led to finding a similar one in some other birds usually considered to 

 be three-toed, namely the Woodpeckers of the genera Picdides and 

 J'iya. In these the hallux consists of its normal number of phalanges, of 

 minutesize, asisalso the metatarsal. The "great toe" thus formed lies 

 completely under the skin, and is only discernible on reflecting the 

 integuments carefully, when the chain of minute ossicles, connected 

 to each other and to the tarso-metatarse by fibrous tissue, appears. 



" These facts render it not improbable that a similarly reduced 

 hallux may really exist in many birds commonly described as three- 



' Biill. U.S. Nat. Mus. i. p. 22. 



= Cf. Voyyge of H M.S. ' Challenger: ' Report on the Anatomy of the Petrels, 

 pp. 13, 14. 



