1888.] MORPHOLOGY OF SUPERNUMERARY PHALANGES. 511 



14. Leydig, F. — Ueber den Eau der Zehnen bei Batrachiera und 



die Bedeutung des Fersenhockers. Morph. Jahrb. Bd. ii. 

 pp. 165-196 (1876). 



15. Parker, T. J. — Second preliminary note on the Develop- 

 ment of Apteryx. P. R. S. vol. xliii. pp. 482-487 (1888). 



16. Peters, W. C. H. — Reise nach Mossambique. Zool. iii. 

 Amphib. (1882). 



1 7. Ryder, J. A. — On the Genesis of the extra-terminal phalanges 

 in the Cetacea. Amer. Nat. 1885, pp. 1013-1015. 



18. Strasser, H. — Ziir Entwicklung der Extremitatenknorpel 

 bei Salamandra und Tritonen. Morph. Jahrb. Bd. v. 

 pp. 240-312 (1879). 



19. Weber, Max. — Anatomisches iiber Cetaceen. Ibid. Bd. xiii. 

 pp. 616-653 (1888). 



VIII. EXPLANATION OF THE PLATES. 



The figures are mostly drawn from tracings of photographs made for us 

 by Mr. R. Chapman, and to him our thanks are due for the care bestowed upon 

 their production. 



All the figures represent digits of the hind foot. Unless otherwise stated, 

 they represent median longitudinal sections, as seen under a low power. 



Plate XXIV. 



Fig. 1. Hyla o.rborea, late tadpole. 



2. Ehacophoriis eques, adult. 



3. Hylajreycineti, adult. 



4. Hyla cmrulea, not fully grown. 



5. Nototrema marswpiatum, adult ; penultimate joint, to show it8 ligament 



and annulus apparatus. 



6. The same ; lateral section. 



7. The same animal ; to show distal joint, 



8. Xenophrys monticola, adult. 



Plate XXV. 



Fig. 9. Hyla arborea, tadpole ; to show the primary differentiation of the parts 

 of the digital skeleton. Zeiss D, Oc. 2. 



10. Rana teinporaria, larva ; to show syndesmosis of terminal joint. Zeiss 



D, Oc. 2. 



11. Bomhinator bomhinus, adult. 



12. Proteus anguinus, syndesmosis of terminal phalanx. Zeiss D, Oc. 2. 



13. Hyla 'peronii, adult. 



14. Portion of the supernumerary phalanx in the same, more highly mag- 



nified. Zeiss F, Oc. 3. 



15. Bpelerpcs fiiscus, adult. 



16. Rana temporaria, adult. 



Reference Letters. 



an. Annulus. cp. Cartilage corpuscle. I. Inter-articular ligament. Ic. La- 

 cuna, nc. Nucleus, p.j}. Penultimate phalanx, p.s. Supernumerary phalanx. 

 p.t. Terminal phalanx, sh. Fibrous tunic of digital skeleton, sy'. Syndesmosis 

 of terminal joint, sy". Syndesmosis of penultimate joint. ^, Extensor tendon. 



