464 DR JOHN ALEXANDER SMITH ON CALAMOICHTHYS 



of nearly the same depth (vertically), tapering very slightly towards the anal fin, 

 behind which it diminishes in depth to its caudal extremity). The caudal ex- 

 tremity is short, and tapers rapidly to a thin and conical point, around which 

 the caudal fin-rays spring. 



Scales.— The scales are osseous, and ganoid in character, and generally 

 rhomboidal in shape ; they are arranged in a regular series of rows, which cover 

 the whole body. On the back each row begins in the median line, and runs 

 obliquely downwards and backwards along both sides, until it terminates in the 

 median line of the abdomen, and thus completes the circuit of the body. These 

 rows are formed throughout of a single series of scales ; in this specimen, how- 

 ever, there is a solitary exception to the rule, which occurs opposite to the com- 

 mencement of the anal region, where two smaller and separate rows on the back 

 run about halfway down each side of the body, and then join in a single row 

 below ; this is the only exception to the rule which I have yet noticed. 



The scales behind the head are small in size, and they gradually become 

 larger as they proceed backwards over the body (where the rows of scales 

 measure above ^ of an inch across) ; they again, however, diminish in size over 

 the caudal extremity of the fish. The scales also vary somewhat in size and 

 shape in different parts of the same series, being slightly larger towards the lateral 

 line of the body. 



The general form of each scale is rhomboidal ; a small tooth-like process pro- 

 jects forwards from the middle of its upper or anterior margin, and a lengthened 

 lateral tubercle also projects outwards and forwards, from the inner and anterior 

 angle of the scale. The anterior or upper edge of a scale, and one of its sides, the 

 inner, that from which the projecting tubercle springs, are gently sloped or beveled, 

 so as to pass slightly under the adjoining scales ; its outer or free margin is nearly 

 straight, and its posterior or lower margin is gently rounded in its outline. The 

 under surface of each scale has a strong bar running down its centre ; it begins 

 anteriorly in the pointed process, or tooth of the scale, and posteriorly it divides 

 into two branches, to accommodate the tooth, or anterior process, of the adjoining 

 scale, which is laid in this space or socket, left at its posterior termination ; the 

 larger lateral process at the same time turning up along the under surface of 

 the posterior and internal angle of the scale in front. The mesial scale of 

 each series, on the dorsal surface, up at least to the first dorsal finlet, is oval 

 in shape, the narrower anterior extremity being forked, having two anterior 

 teeth lying side by side, which fix it to the connecting tissue and scales in front ; 

 and the longitudinal central bar on its under surface divides into two branches 

 posteriorly, which run out laterally to the posterior edges of the scale, and each 

 of these lateral terminations of the bar receives the tooth of the anterior or 

 upper margins of the two adjoining scales — the first of the lateral series, and 

 their tubercles lie along, and below its surface. The scales next in order, on 



