244 Dr. B. H. Traquair — On CycloptycMus carbonarius. 



post-temporal Parker), is a short, nearly triangular plate (Fig. 3, 1st 

 s. cl.), seen immediately behind the cranial shield ; below it is seen 

 the more elongated 2nd supra-clamcidar (scapular Owen, supra- 

 clavicular Parker) : this bony plate (Fig. 3, 2nd s. cl.) is broader above 

 than below, and obliquely pierced by the lateral slime-canal. The 

 next bone (cl.) is the clavicle {coracoid Owen), consisting of two 

 portions, upper and lower. The upper portion is much the larger, 

 and articulates above with the 2nd supra-clavicular ; the lower, short 

 and square, is set to the other at an obtuse angle, so as to project 

 inwards towards the ventral middle line ; between the two portions 

 behind is a pretty deep notch, where the pectoral fin projects. In 

 front of the lower end of the clavicle, and closely articulated with 

 it, is yet another bony plate (i. cl.), long and pointed, bent longitudin- 

 ally upon itself, and passing forwards and inwards to meet its fellow 

 of the opposite side. This is the inter-clavicnlar of Parker, and clearly 

 corresponds to the bony plate placed below the lower end of the 

 clavicle in Polypterus, and also in Accipenser. There is also some 

 trace of a small post-clavicidar (p. cl.) immediately behind the junc- 

 tion of the clavicle and the 2nd supra-clavicidar. 



Scales. — Dr. Young, in the paper alluded to, refers to the scales as 

 being " cycloidal," but remarks further that " the obliquity of their 

 axis, from the production of their posterior inferior angle, gives them 

 in situ a rhomboidal appearance." ^ Mr. Barkas also states the scales 

 to be "cycloidal," and that they "more closely resemble those of 

 Coelacanthus than do the scales of any other Coal-measure fishes." ^ 

 The well-preserved specimens before me, however, show that the 

 scales, instead of being cycloidal, are in reality rhomboidal, and that 

 in form and arrangement they conform in every essential respect to 

 the type of scales seen in Paloeoniscus and its allies. The principal 

 peculiarities are, their thinness, the rounding of their posterior 

 inferior angles, and their upper margin being perhaps rather more 

 than usually overlapped. They are as usual arranged in oblique rows ; 

 the longitudinal series are, however, not always regular. The form 

 of the scales of the flank, as seen in a specimen in which they are 

 much disjointed (see Fig. 6), is rhomboidal, with the anterior superior 

 angle acute and pointed, the posterior inferior angle rounded ; from 

 the middle of the superior margin a pointed peg projects upwards 

 for articulation with the under-surface of the scale above. The 

 ornament of the free surface consists of fine, raised, thread-like 

 ridges, running in the main parallel with the anterior, inferior, and 

 posterior margins, and of which arrangement the drawing Fig. 5 will 

 give a better idea than any further description. One ridge running 

 along the upper part of the posterior mai'gin is generally more or less 

 zigzagged, so as to give almost a crenulated aspect to that margin.* 

 The scales of the flank do not alter much in size or shape till we 



1 Op. cit. p. 319. 2 O}}. cit. p. 37. 



3 The ornament of the surface is in most of the specimens very hadly preserved, or 

 rather, bndly seen, from the tendency of the superficial layer of the scale to split off. 

 It is unusually well exhibited in the specimen, PI. XII. Fig. 1, from whose scales the 

 above description, and the magnified view in Fig. 5, were taken. 



