CYCLOPTYCHIUS CONCENTRICUS. 125 



forwards, and increase in obliquity from behind forwards. Small conical teeth of different 

 sizes may be observed in several specimens. 



The bones of the shoulder-girdle present nothing peculiar in their configuration, and 

 so far as their external sculpture is visible it consists of wavy sub-parallel ridges. 



The scales of the flank (fig. 7) are somewhat large for the size of the fish, and are 

 higher than broad, with their postero-inferior angles obtuse ; towards the back, belly, 

 and tail they become smaller, and assume the usual rhomboidal shape. The articular 

 spine is well marked though small; the keel of the attached surface is central and 

 sharply defined. The scale-markings are characteristic. Along the sides of the body, 

 as far as the tail-pedicle, the exposed surface of the scale is ornamented by somewhat 

 coarse and closely placed ridges, which, commencing at the upper margin, descend in 

 such a way as to form one median ridge surrounded by several others, which, running 

 parallel with each other and with the anterior and posterior margins, join each other below 

 round the extremity of the median one; or — to put the matter in a different way — we 

 have a set of concentric ridges j)arallel with the antero-inferior and posterior margins 

 with an odd one in the middle, or sometimes with two uniting in a loop ; in addition, 

 there are often one or two fine vertical striae along the anterior margin. A somewhat 

 different pattern is observable along the back (fig. 8), extending downwards to and 

 including the second longitudinal row of scales above the lateral line. Here there is 

 ordinarily only one marginal ridge, running closely along the anterior, inferior, and 

 posterior borders, within which the area is, according to the size of the scale, occupied 

 by from two to five diagonal and parallel ridges passing from before downwards and 

 backwards. The caudal body-prolongation has its minute lozenge-shaped scales 

 ornamented by diagonal ridges only ; striae of a similar description characterise also 

 the large V-sliaped scales which run along its upper margin. 



'V\\e 2)cctoral fin is small, its length being hardly more than half that of the head; it 

 is acuminate in shape and consists of about twelve rays, of which the principal ones are 

 unarticulated till towards their terminations. TMie ventrah seem to have been likewise 

 small, and the articulations of their rays somewhat distant. The median fins are on the 

 contrary of tolerably large size. The dorsal is situated far back, and is triangular- 

 acuminate in shape; its rays, the number of which cannot be accurately ascertained, are 

 slender, smooth, and distantly articulated. The anal is placed nearly opposite the 

 dorsal ; it is shar[)ly acuminate, with concavely excavated posterior border; the rays are 

 of the same charncter as those of the dorsal. The caudal fin is well developed, deeply 

 cleft, and jnequilobate ; its rays resemble those of the other median fins. 



Bemarhs. — That the above described species is referable to the genus Cycloptychius 

 is indicated by the following characters : The slender, elongated form of the body, the 

 backward position of the dorsal fin, the obtuseness of the postero-inferior angles of the 

 scales, and, last but not least, the possession of a peculiar scale-ornament, consisting of 

 ridges running parallel with the anterior, inferior and posterior margins of the scale. At 



