RHADINICHTHYS TUEERCULATUS. 157 



cranial roof, as well as, in impression, on a small portion of tlie suboperculum. Towards 

 the extremity of the mandible also a patch of the outer surface of the hone is seen, but 

 here the ornamentation consists of closely set delicate, wavy ridges, running in a longi- 

 tudinal direction. 



The bones of the shoulder-girdle — supra-clavicular, clavicle, and infra-clavicular — 

 are pretty well shown, the two latter from their internal aspects only. The outer 

 surface of the supra-clavicular displays some traces of longitudinal striated sculpture. 



The scales are rather small for the size of the fish, especially at the tail, towards 

 which they rapidly diminish. In the tlank-scales (Plate XXXV, fig. 2) the covered 

 area is narrow ; the sculptnred one presents a few fine ridges and grooves along the 

 anterior margin, the rest of the s])ace being covered with small closely-set tubercles, 

 sometimes rounded, sometimes elongated or confluent. Towards the tail (fig. 3) and 

 also towards the dorsal and ventral margins the tubercles largely give way to a ridged 

 ornamentation ; the ridges running parallel with the anterior and inferior margins, 

 sometimes also with the superior, while the postero-central ])orti()n of the area is 

 occupied by tubercles which tend to become confluent into diagonal ridges, which are a 

 little coarser as well as more wavy and irregular than the marginal ones already 

 mentioned. Powerful longitudinally-ridged V-scales protect the upper margin of the 

 caudal body-prolongation, which is of great strength, while the acutely lozenge-shaped 

 scales which clothe its sides are of small size, arranged in many rows, and, so far as they 

 are traceable, ornamented with sharp diagonal ridges. 



On the attached surface of the body-scales the vertical keel is rather delicate, yet 

 very distinctly defined, as is also the socket for the reception of the articular peg of the 

 scale next below; and, as usual, the pegs and sockets disappear in the scales of the 

 posterior part of the body. No denticulations are observable on the posterior margins of 

 any of the scales. 



The pectoral fin is 1 ^ inches in length and has its principal rays unarticulated for the 

 greater part of their length. The origin of the ventral is situated 1-^% inches behind that 

 of the pectoral; the fin itself is not in good preservation, its rays being much broken 

 up, so that its shape and size are lost. The dorsal fin is situated nearly opposite the 

 anal, arising opposite a point 4 inches back from the tip of the snout ; the anal 

 commences only a little behind the dorsal and extends correspondingly further back. 

 Both of these fins are large, each measuring about an inch in length at the base, and 

 the same in height anteriorly, although the larger rays do not seem to be preserved up 

 to their extremities. They are also very similar in shape, being triangular and 

 acuminate ; their numerous and rather delicate rays have their transverse articulations 

 somewhat distant, so that the joints are rather longer than broad; no sculpture is 

 visible. The caudal is incompletely preserved, the extremities of both lobes being 

 wanting, but enough is seen to show that it was powerfully developed, deeply 

 cleft, and having a body-prolongation of great strength along the upper lobe ; the rays 



