1. CENTKI8CUS. 523 



exceedingly strong and long, its length being a little more than one- 

 half the distance of the opercle from the caudal. 

 Australian Seas. 



a. Adult : stuffed. Australia. — Type of the species. 



Description. — The length of the head is somewhat less than its 

 distance from the caudal fin ; it is rather elevated posteriorly and 

 compressed into a sharp ridge above. The eye is large, equal in 

 width to the extent of the part of the head behind it ; the skin 

 which covers the iris is scaly ; margin of the orbit smooth. The 

 nostrils are close together, situated one before the other, on the side 

 of the head, at a small distance from the orbit. The limbs of the 

 praeoperculum meet at a right angle ; the posterior descends obHquely 

 forward, is partly confluent with the orbit, and very indistinctly den- 

 ticulated. The scales advance very far on the rostral tube. 



The body is strongly compressed and much elevated ; its greatest 

 depth is above the ventrals, whore it is somewhat less than the di- 

 stance of the operculum from the caudal fin. Its upper profile makes 

 a hump on the neck, and then ascends gradually to the base of the 

 second dorsal spine, where it descends abruptly in a nearly vertical 

 line to the free portion of the tail. The lower profile is semicircular 

 between the throat and the end of the anal fin. The whole body is 

 covered with very small scales, each of which terminates in a spine 

 posteriorly. There are two series of bony plates on the side of the 

 back, each series being composed of four plates which have a centre 

 with horizontal and vertical stripes radiating from it; the lower 

 series commences in the scapulary region, the upper runs in a 

 parallel line above it. The margin of the thorax is cuirassed with 

 three series of similar plates, that of the belly with a single series ; 

 the edge of the thorax and that of the belly are sharp. 



The pectoral fins have a short and oblique base, and are inserted 

 on the middle of the depth of the body ; they are rather longer than 

 the distance of the anterior margin of the orbit from the posterior of 

 the operculum, and extend to above the middle of the ventral fins. 

 Ventral fins very small. The distance of the very small first dorsal 

 spine from the caudal fin is two-thirds of that from the occiput ; the 

 second spine is exceedingly strong and long, compressed, striated, 

 and strongly denticulated posteriorly ; the other spines behind it are 

 short. The soft dorsal fin is higher than long, and its distance from 

 the base of the caudal is more than the extent of its base. . The anal 

 fin commences immediately behind the vent in the vertical from the 

 last dorsal spine, and extends a little more backwards than the soft 

 dorsal ; it is, like that fin, composed of simple rays, but much lower. 

 (The caudal fin is mutilated.) 



inches, lines. 



Total length 5 G 



Length of the head 2 3 



of the snout (from the orbit) .... 1 7 



Height of the body 2 1 



Length of the second dorsal spine 1 4 



