SCALES 



191 



FiQ. 108. — A, Scale oi Antennarius hispidus, x 100 ; B, 

 scale of a young Malthe vespertilio, x 100. (After 

 HertAvig.) 



the result of the curious modifications which their scales 

 undergo. In some of 

 the Coffer-Fishes {Os- 

 tracion) these struc- 

 tures assume the form 

 of polygonal bony 

 plates which 'suturally 

 articulate with one 

 another and enclose 

 the trunk in a rigid 

 cuirass, from which the 

 scaleless tail protrudes 

 behind (Fig. 438); 

 while in some Globe- 

 Fishes and Porcupine- 

 Fishes (e.g. Tetrodon, 

 Diodon) the prolongation of the scales into strong erectile spines 



equally well serves the pur- 

 pose of protection (Fig. 439). 

 Most Teleostomi have 

 the scales along the " lateral 

 line " perforated by single or 

 multiple apertures, through 

 which the sensory canal 

 communicates with the 

 exterior. 



In a few Teleosts scales 

 are entirely absent, as in 

 most Siluridae ; or they 

 exist only as microscopic 

 vestiges hidden in the skin, 

 as in Eels ; or, as in such 

 naked forms as Antennarius 

 marmoratus and Zepado- 

 gaster, and in some Silu- 

 FiG. 109.— A, Scale of Baiistes capriscus, x 20 ; ridae, they become reduced 



B, scale of Monacanthus scopas^ x 20. (After fQ mere Daoillae of the 

 Hertwlg.) ' . " 



dermis. 

 The concentric rings observable (Fig. 105) on the surface 

 of many Teleostean scales are an index to the age of the 



