COELACANTH FISHES — WHITE 353 



forms were quite small fishes, some only a few inches in length like the 

 Carboniferous Rhahdoderma and the Triassic Whiteia, but one, 

 Mmosonia from the Cretaceous rocks of Brazil, probably exceeded 

 in size the living specimens, the larger of which was 5 feet long. 



Their most striking feature is provided by the paired fins (the 

 first two lower fins seen in fig. 1 and pi. 1, figs. 1 and 2), which 

 correspond to our arms and legs and which are borne on muscular 

 scaly lobes instead of being fanlike and coming straight from the 

 body, as in more familiar fishes. A similar single fin is to be seen just 

 behind the vent about midway between the hinder pair and the tail, 

 and another lies opposite it on the back. This last fin is the posterior 

 dorsal fin; there is another one in front of it and placed halfway 

 toward the back of the head, the anterior dorsal fin, but this always 

 lacks the scaly lobe. 



The form of the tail is also peculiar. There is no marked constric- 

 tion in front of the fin; the scaly body just narrows rapidly and 

 evenly, dividing the fin rays into two equal parts above and below 

 it, and in many coelacanths it continues beyond them to form a small 

 supplementary tail (pi. 1, fig. 1). There was one other extraor- 

 dinary feature. In fossil fishes as a rule little or nothing is found 

 of their "insides" since the contents of the body cavity — heart, liver, 

 intestines, and so on — were soft and decayed rapidly, but in the 

 coelacanths the air sac was sheathed in bony scales and therefore 

 largely rigid. In all probability this organ was a functional lung 

 in the ancestors of the coelacanths, and is so in their living nearest 

 relations, the lungfishes (Dipnoi). In most modern fishes it persists 

 as a long membranous bag which acts as a hydrostatic organ, the 

 gaseous content being adjusted to keep the fish buoyant at any par- 

 ticular depth. Its remains are sometimes seen as a silver streak in the 

 breakfast herring. 



Latimeria, the specimen caught in 1938, shows all the external fea- 

 tures characteristic of the coelacanth group, some in an exaggerated 

 form. The small supplementary tail is well developed, and the lobes 

 of the scaly-based fins are much lengthened, in fact considerably more 

 so than in the fossils, so that they stand well away from the body, 

 looking very much as if they really were on the way to becoming walk- 

 ing limbs. This fish was 5 feet long, weighed 127 pounds, and was 

 steel-blue in color. 



Tlie new fish, which is a male, is some 6 inches shorter. It looks 

 similar except that it lacks the supplementary tail fin and the anterior 

 fanlike fin on the back (pi. 1, figs. 2 and 3). It was the absence of 

 these two typical coelacanth features that was apparently the chief 

 reason why Professor Smith referred it to a different genus, Malania; 

 -but if one looks carefully at the published photograph of it (pi. 1, 

 fig. 2) one sees an unnatural-looking dip in the back where the front 



