172 



PAL/EONTOLOGY. 



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tiiict species, mostly of extinct genera. It is 

 richly represented at the pre- 

 sent day by the Sphyrenoid, 

 Scomberoid, and Xiphioid 

 families. 



There are two kinds of ex- 

 isting sword-fish, Xvphias and 

 Histioplwrus ; in the former 

 the sword-like prolongation of ScalesofaScom- 

 the confluent premaxillaries is beroid fish - 

 flattened, in the latter it is rounded. 



Fossil remains of a rounded rapier-like 

 " sword," but much longer and more slender 

 than in the existing Histiophorus, have been 

 found in the eocene clay at Sheppey and 

 Bracklesham. They are referred to an ex- 

 tinct genus of the xiphioid family by Agassiz, 

 called Ccelorhynchus, or " hollow beak." The 

 most perfect specimen hitherto found is 

 figured in fig. 80, of half the natural size. It 

 forms part of the instructive collection of 

 Captain Le Hon at Brussels. The upper 

 transverse section shews the single cavity at 

 the middle of the rostrum ; and the lower 

 section shews the double or divided cavity 

 near its base. 



Order V.— ANACAJSTHINI. 

 Char. — Endo-skeleton ossified ; exo-skeleton 

 in some as cycloid, in others as ctenoid 

 scales ; fins supported by flexible or 

 jointed rays ; ventrals beneath the 

 pectorals, or none ; swim-bladder with- 

 out air-duct. 



