324 



BULLETIN OP THE BUREAU OK FISHERIES. 



Table 9. — Pigfish. — Compaiung the Average Lengths Measured for the Different Year 

 Groups With the Lengths Calculated, and the Number op Specimens Measihied and Cal- 

 culated IN Each Case. 



SYNONYMY OF TERMS. 



Owing to the great number of terras applied to the different structures of scales 

 and the confusion resulting from it, this synonymy has been arranged to specify the 

 terms employed in this paper. 



The exterior surface of scales is marked with numerous, more or less distinct relieved 

 lines, concentric, or nearly so, in most cases, with the periphery. They are variously 

 known as annuli (Esdaile), circuli (Cockerell), striae, fibrillae, concentric rings, and 

 growth-rings. Such lines are here denoted as circuli. (PI. L, C) 



For their common center, usually somewhat posterior to the center of the scale, 

 the terra focus adopted by Cockerell is used in this paper. It has also been called the 

 center, centrum, center of growth, and nucleus. (PI. l, F.) 



Concentric with the circuli are bands or zones, which are here denominated annuli. 

 They are darker than the space between them and have been regarded as zones in 

 which the circuli are closer together. They appear in some cases to be regions in which 

 the regularity of the circuli is interrupted. They are variously known as annuli, pero- 

 nidia, annual rings, winter bands, and growth-rings. (PI. l, A.) 



Radii, as they are called in this paper, are lines found usually on the anterior side 

 of the scale, perpendicular to the circuli, directed from the focus to the periphery and 

 usually increasing in number as the latter is approached. They have been known as 

 grooves, radiating grooves, and radii. (PI. L, R.) 



The outer edge of the scale is called in this and other papers the periphery. It 

 has been called the margin. (PI. L, P.) 



In some scales the posterior field is found to be covered with spines, barbs, or 

 teeth. The author uses the term spines for these. They have been called denticles, 

 spinules, and teeth. (PI. L, Sp.) 



A scale may be divided into four areas or fields. They are referred to in this 

 paper as the anterior field or that portion covered in the scale pocket and directed toward 

 the head of the fish; the posterior field or that part opposite the anterior field and in 

 ctenoid scales covered with spines; and the lateral fields or those on either side of the 

 scale. In connection with areas of the scale surface the words apical and basal have 

 been used for posterior and anterior, respectively. 



The inferior side is that nearest the body. The exterior or superior side is the 

 sculptured side. 



