9^0 MR. A. WILLEY ON AN APODOUS AMIA CALVA. 



especially since it falls into line with ascertained anatomical 

 relations. 



According to Giintber (1880), fishes living in limited localities 

 or concealing themselves in mud are apt sometimes to lose their 

 ventral fins. One of the local na,mes for ^mm is Mudfish, another 

 is Beaver-fish (poisson castor), a third is Bowfin. The last of these 

 may have reference to the rounded arcuate shape of the caudal 

 fin, liJve a stretched how. Wherever it occurs it frequents 

 marshy places, and its habits resemble in many ways those of the 

 oriental Tankfish [Oj:)hiocephahts striatus), known in Southern 

 India as the " murrel' and in Oeylon as the "lula." This species 

 has ventral fins, but the closely-related Paddy-field fish (Chaiina 

 orientcdis) is \\'ithout them. The Swordfishes and some other 

 pelagic and deep-sea fishes show that the pi-esence or absence of 

 ventral fins does not dejDend on one class of habits alone. 



There are certain other wavering characters in Teleostean 

 fishes, which, taken in conjunction with the admitted decadence 

 of the ventral fins, suggest the hypothesis tha,t the presence or 

 absence of such deep-seated characters is linked up with their 

 use or disuse, and that they do not necessarily dwindle away 

 to vanishing point, but may simply drop out of the factorial 

 system. 



Eefeeences. 



1. A. C. L. GtyNTHER, 1880.— The Study of Fishes, p. 615. 



2. H. H. Brindley, 1891. — " On a Specimen of the White Bream 



(Ahramis blicca Bloch) without Pelvic Fins." Proc. Zool. 

 Soc. pp. 108-9, pi. X. 



3. W. Bateson, 1894. — Materials for the Study of Variation. 



4. C. Gegbnbaur, 1 895. — "Das Flossenskelet der Crossopterygier." 



Morph. Jahrb. xxii. pp. 119-160, 5 figures. 



5. C. H. Eigenmann and U. 0. Cox, 1901.—" Some Cases of 



Saltatory Ya.riation." Amer. ISTat. xxxv. p. 33. 



6. J. F. Gemmill, 1912.— -The Teratology of Fishes, p. 55. Glas- 



gow. 4to. 



