856 DR. E. A. GOELDI ON THE [NoV. 29, 



short aud insignificaut filaments arising from the gill-opening 

 and situated at the base of the fore-limb. They are generally 

 considered as external branchial appendages undergoing atrophy. 

 According to Dr. Giinther they merit the rank of a specific 

 character in comparison with the Australian Ceratodus and the 

 South -American Lejridosiren ( ' Introduction to the Study of 

 Fishes,' p. 355 ; ' Catalogue of Fishes in the British Museum,' 

 vol. viii. (1870) p. 322). Prof. Lankester has recently expressed 

 his doubts about the specific value of the characters of the branchial 

 appendages of Protopierus, stating, on the one hand, that moderate- 

 sized specimens of Protopterus do not possess externa! gills, and 

 supposing, on the other hand, thai small specimens of Lepidosiren 

 (not having been yet examined) may possess such gills (see Trans. 

 Zool. Soc. xiv. p. 18). 



As the matetr stands, the facts observed in our living specimen 

 of Lepidosiren become of much interest. Supposing that 1 am 

 right in my opinion concerning the physiological signification of 

 these strange appendages, we must be surprised at the analogy of 

 the case with that of certain Amphibians of the section Urodela. 

 From the experiments of Mademoiselle De Chauvin \ we know that 

 the celebrated Mexican Amhlystoma remains in the Siredou-state, 

 characterized by external branchije, under the artificial constraint 

 of water-life. Other experiments of the same observer have shown ^ 

 that the ovine larvae of Triton alpestris throw off their excessively 

 developed external branchiae, replacing them rapidly by new ones, 

 better adapted to the casual conditions of a life in water — which 

 for this species is not the normal one. AVe know further % that 

 Kneeland observed the extreme facility with which two specimens 

 of Menobranchus lateralis regenerated their external branchiae, when 

 bitten away by fishes inhabiting the same aquarium. Ultei-ior 

 secondary development of external branchiae is thus a fact not 

 isolated in the animal kingdom. Does the consideration that such 

 cases are not confined to the Amphibia really involve an insuperable 

 difficulty ? I do not think so. In its mode of life Lepidosiren is, 

 from the biological standpoint, as true an amphibian as these 

 animals, which belong properly to that class according to present 

 scientific A'ieMS. Aud reflecting that identical external conditions 

 of life will naturally produce similar physiological functions, and 

 therefore favour analogous ways of organization, this reasonable 

 argument is sufficient to i-eniove the apparent contradiction which 

 seems to result from the distance apart of these creatures in the 

 zoological series. 



But a new and greater difficulty seems to ai'ise from the fact 

 that the appendages in the present case are at the free end of 

 the fin. If they came out of the opercular opening, issuing 

 independently close to the origin of the fore-members, as in 

 Protopttrus, the matter would be comprehensible. But branchial 

 appendages at the very end of the fore-limb itself, that is at first 



1 Knauer, ' Naturgeschielite der Lurclie,' Wien, 1878, p. 231 seq. 

 - JbuL p. 2(53. =* Ibid. p. 238. 



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