SCALES 



191 



scale of a young Malthe vespertilio, x 100. 

 Hertwig.) 



(After 



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- FIG. 10S. A, Scale of Antennarius hispidus, x 100 ; B, 



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 Lepado- 

 gaster, and in some Silu- 

 FIG. 109. A, Scale of Batistes capriscus, x 20 ; ridae, they become reduced 



B, scale of Monacanthus scopas, x20. (After to mere pap ill ae o f t he 



Hertwig.) 



mere papillae of 

 dermis. 



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



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



