14 



Milne-Edwards and Miiller have added to our knowledge of their organ- 

 ization, and each has discussed their affinities from various points of 

 view. 



Although such learned biologists as the Professors Bischoff and Milne 

 Edwards have believed in the accuracy of the reference of the Lepido- 

 sirenoids to the Amphibian reptiles, the greatest number of zoologists 

 has regarded thein as true fishes. The first of these are undoubtedly 

 Owen and Miiller, each distinguished by the most profound knowledge of 

 the anatomy and characteristics of the classes of the Vertebrata. 



Professor Owen, in the "concluding observations " of his admirable 

 memoir of the Lepdosiren anne dens, has fully reviewed the relations of 

 that species, and has pronounced an unqualified belief in its piscine 

 affinities. He has shown that it is proved to be a fish, " not by its gills, 

 not by its air bladders, not by its spiral intestine, not by its unossified 

 skeleton, not by its generative apparatus, nor its extremities, nor its skin, 

 nor its eyes, nor its ears, bnt, simply, by its nose." In all of its characters, 

 except the last, it agrees with some of the lower Amphibians. He yet 

 warns the student " that the physiological consequences of the modifica- 

 tions of the nasal cavity, above alluded to, would have been far too 

 insignificant to have established the ichthyic nature of the Lepidosiren, 

 if, with coexistent gills and lungs, the modifications of the other organic 

 systems had agreed with those of the Perennibranchians instead of with 

 those of Fishes." As his remarks that follow are pertinent to the subject 

 of the present memoir, we take the liberty of quoting them : 



" For, although it be true, that the fish-like modification of any single 

 system is insufficient of itself to determine the removal of the Lepidosiren 

 from the Amphibia, in which it has hitherto been placed, to the class of 

 Fishes, yet it is impossible to av id arriving at that conclusion, when we 

 consider the concurrence of ichthyic characters in so many parts of the 

 organization of this most interesting species. The combination of cycloid 

 scales, mucous ducts, quasi-fins, supported each by a many-jointed ray, 

 a gelatino-cartilaginous vertebral style united to the whole surface of the 

 basi-*occipital, and not to two basilar condyles, the preopereular bone, the 

 simple structure of the lower jaw, the double spines of the neur- and 

 hcem-apophyses, the green color of the ossified parts of the skeleton; 

 these external and osteological characters being associated with an 

 intestinal spiral valve, with the absence of pancreas and spleen,* the 

 position of ihe anus anterior to the allantoid bladder, adicceleus heart, six 

 pairs of branchial arches, with the gills concealed, the simple organ of 



*MiUler or Peters has demonstrated the existence of a spleen in the Rhino- 

 crijplis amphibia of Peters, which is doubtless a species of Owen's genus 

 Proiopterus. It is large, and situated behind the stomach and commencement 

 of the intestinal canal, and beneath the peritoneal coat of the tractus intesti- 

 nalis. It must be separated from the black pigment which forms a copious 

 substratum beneath the peritoneal covering of the intestines. 



