26 ON THE SKELETON ETC. OF CERATODOS. [Jan. 18. 



tematik von Lepidosiren und Protopterus. Zool. Anzeiger, 

 vol. ix. p. 521 (1886). 



24. Thacher, J. K. — Median and paired Fins, a contribution 

 to the history of vertebrate limbs. Trans. Connectic. Acad, 

 vol. iii. p. 281 (1877). 



25. Thacher, J. E. Ventral fins of Ganoids. Ibid. vol. iv. 



p. 233(1878). 



26. Traquair, E. H. — On the Restoration of the Tail in Proto- 

 pterus annectens. British Assoc. Reports, 1871, pt. 2, p. 143. 



27. Traquair, R. H. — On the Structure and Affinities of Tris- 



tichopterus alatus. Trans. R. Soc. Edinb. vol. xxvii. p. 383 

 (1876). 



28. WiEDERSHEiM, R.— Ueber das Becken der Fische. Morph. 



Jahrb. vol. vii. p. 326 (1881). 



29. WiEDERSHEiM, R. — Lchrbuch der vergleichd. Anat. der 



Wirbelthiere. Zweite Au6age. Jena, 1886. 



30. WiEDERSHEiM, R. — Das Skelet und Nervensystem von 

 Lepidosiren {Protopterus). Jenaische Zeitschr. vol. xiv. 

 p. 155 (1880). 



IX. DESOEIPTION OF THE PLATES. 

 Plates I.-III. 



With the exception of fig. 2, all are drawn in the same relative position. 

 The postaxial (internal) border looks towards the left hand. 

 Pig. 1. A " branching " pelvic fin of Ceratodus. Eight side, dorsal aspect. Nat. 

 size. 



2. The two pelvic fins of a second specimen. Ventral aspect. X 1^. 

 2a. The anterior portion of the pelvic girdle of the same. Nat. size. 



3. The proximal third of the left fin of fig. 2. Ventral aspect. Nat. size. 



4. Proximal third of a right pelvic fin ; indicated as seen from the ventral 



aspect, for sake of comparison with figs. 1 and 3. (After Giinther.) 

 Nat. size. 



5. The left pectoral fin of fig. 2. Ventral aspect. Nat. size. 



6. Proximal portion of the corresponding fin of a fourth specimen. Ven- 



tral aspect. Nat. size. 



7. Proximal portion of the left pelvic fin of the same specimen. Ventral 



aspect. Nat. size. 



8. The proximal third of the left pectoral fin of a fifth specimen. Drawn 



to same scale as figs. 5 and 6. (After Giinther.) 

 8a. Basal portion of a left pectoral fin of Protopterus. x4. 



9. The left pectoral fin of Ccdraeion fhUippi. Young J. dorsal aspect. 



Half uat. size. 



10. The basal portion of a similar fin ; same aspect. Adult. (After 



Huxley.) Reduced to the same scale as fig. 9 for sake of comparison. 



11. The left pectoral fin of a young Polypterus. Ventral aspect. x2. 



12. The left pelvic fin of a young ChiriKBra (C. moistrosa), (S . Ventral 



aspect. XH. . 

 In figs. 5 and 7 the parameres not represented in full were all rod-like and 



unbranched. 

 The dotted lines in figs. 9 and 12 represent lines of fusion observed ; those in 

 figs. 5, 6, and 10 are inferred. 



Ecference Letters, 

 cp. Base of clasper. /. Inter-articular ligament, m.p. Proximal mesomere. 

 ms. Mesopterygium. mt. Metapterygium. pi. Pelvic girdle, pr. Preaxial 

 fin-border, ps. Postaxial fin-border, pf. Propterygium. r. Metapterygial 

 rays. 



