Branchiae in the young Caeciliae. 359 



characters observable in their organization I regard as of mi- 

 nor importance. 



Thus it seems to me, that we must either account these 

 animals as Fishes endowed with true and well-developed 

 lungs of a vascular and cellular structure and fitted for re- 

 spiring air, similar to those of the Amphibia and Reptiles, and 

 with some other essential characters also common to the Am- 

 phibia ; or as Amphibians possessing nasal sacs with an ex- 

 ternal orifice only (according to Mr. Owen) and adapted for 

 smelling like those of the Fishes, and likewise having a few 

 other ichthyic characters ; or in fewer words, either as Fishes 

 with the lungs and some other principal characters of the 

 Amphibia, or as Amphibians with the nose and a few other in- 

 ferior characters of Fishes. 



Here, then, we must elect, whether we assume the lungs or 

 the nose as the chief characters whereby to decide in which 

 class of the Vertebrata these animals ought to be most cor- 

 rectly placed. However, it will be readily admitted by all na- 

 turalists, that the former or the respiratory organs far exceed 

 in importance the latter or the olfactory organs, and therefore 

 must compel us at once to select them for the classification 

 of these animals in preference to the latter. And surely even 

 by considering these animals as Amphibians^ possessing the 

 nose or nasal sac of Fishes, it will be much less incongruous 

 and much less departing from the usual and received charac- 

 ters of the divisions of the Vertebrata, than if we were to 

 esteem them as Fishes furnished with the lungs of the Am- 

 phibia ; for this I cannot but think would be too anomalous 

 and too much at variance with the general definition of Fishes 

 — as having gills but no lungs — notwithstanding that the air 

 or swimming-bladders of two or three genera of Fishes of the 



* M. Milne Edwards has likewise stated, in ibe paper already quoted, 

 iivo other characters belonging to the L. paradoxa, which afford strong 

 evidence in favour of its being coi-rectly esteemed an Amphibian. Thejirst 

 is, that." M. Bibron has also satisfied himself of the existence of the two au- 

 ricles of the heart described by M. Bischoff, so that in this important respect 

 the Lepidosiren stands remote from Fish and approaches nearer to most 

 Reptiles." And the second is, that " the lungs of Mammalia, of Birds, and 

 of Reptiles, as every one knows, always originate from the ventral face of 

 the digestive tube, whatever their position may be in the splanchnic cavity, 

 and it is always on the ventral side of the pharynx that the opening of the 

 glottis is found; it is the same with the Lepidosiren." 



Now if, on a more minute examination of the L. annectens, this animal 

 shall be found never to possess any hinder nostrils communicating with the 

 mouth, and that its heart has only a single auricle, then I think it will be 

 necessary to consider it as a genus distinct from the L. paradoxa, and which 

 1 would name Protoineliis. I must also add, that the L. paradoxa has fifty- 

 iive pairsS of ribs, whilst the L. anneciens possesses only thirty-six. 



