260 PROCEEDINGS OF THE ACADEMY OP 



equalling 31-100 of the length of the head ; hehinrl the second dorsal the width 

 is greater than the height, and equals 21-100 of the head. At the fifth plate 

 hehind the latter the height is only equal to sis- tenths of the width. 



The sides hetween the superior and inferior lateral ridges are vertical ; the su- 

 perior carina is straight and ohlique to nearly the end of the second dorsal, and 

 is then horizontal ; the spines only become developed under the end of the first 

 dorsal ; they are small, compressed and acute. The inferior carina is straight 

 on the first five plates, thence oblique to the vertical of the anal fin, and after- 

 wards nearly horizontal ; its spines are like those of the superior carina. The 

 space between the ridges at their commencement equals a quarter of the 

 head's length, (25-100) ; that at the fifth plate of the lower carina, 15-100, 

 and that above the first anal rays, 18-100. Behind the dorsal and anal fins 

 the} 7 form nearly right angles with the dorsal and inferior surfaces of the 

 caudal peduncle. The dorsal surface is nearly flat or slightly concave. The 

 width between the dorso-lateral carina? in front of the back is subequal, and 

 equal to a fifth of the head's length, (21-100) ; it there becomes gradually 

 narrow, and ends behind the second dorsal in an acute point, produced by the 

 convergence of the carina?. The width decreases more rapidly at the first than 

 the second dorsal. The spine of the carinse are most developed anteriorly and 

 are obsolete behind. 



The head has a parallelopiped form, like that of a Trigloid; its occipito- 

 nasal outline is sigmoidally curved ; its inferior surface plane. Its height at 

 the nape equals 42-100 of its length ; behind the superciliary spine, 39-100 ; 

 thence the sigmoidal curve is very oblique, the curve being increased by the 

 development of the superciliary crests ; the spine in which each crest termi- 

 nates is moderate, compressed and recurved ; the lateral occipital carinse are 

 well marked, slightly divergent, and end in spines similar to the superciliary. 

 The head is widest at the opercular bones, where it equals 47-100 of the 

 length ; the sides are nearly vertical. The interval between the superciliary 

 crests equals a fourth of the head's length ; that between the occipital spines, 

 24-100. 



The eyes are elliptical and of large size ; the distance of the orbit from the 

 end of the rostral spine equals 47-100 of the length of the head ; the long 

 diameter of the orbit equals 26-100, and the short one 21-100 of the same. 



The suborbital bones are delicately waved and pectinated beneath, and have 

 a submarginal ridge. The great suborbital bone has at the middle of its ridge 

 a small, compressed, curved spine, from which granulated radiating strias 

 diverge on every side and cover the surface ; the height of the suborbital 

 equals 16-100 of the head's length, while its length is 29-100 of the same. 

 On the preceding bone is another smaller spine. The preoperculum is high, 

 and its margin sigmoidal ; its crest is above the horizon of the suborbital one, 

 well developed, and ends in an acute spine ; beneath the crest the bone is pro- 

 duced into an angle. Granulated radiating strife proceed above and beneath 

 from the commencement of the preopercular crest. The operculum is also 

 ridged above and covered with granulated rays. 



There are on each side two rostral spines ; the first is terminal, elongated 

 conical, straight and horizontal ; the posterior is some distance behind, smaller 

 and curved backwards. There are also two approximated curved frontal 

 spines on an elevated base, and with three rows of granulations proceeding 

 forward from each. 



The mouth is placed quite far back, and the lower jaw is shortest ; the front 

 of the latter is under or slightly behind the vertical of the prefrontal spines, 

 and at a distance from the rostral spine equal to 32-100 of the head's length ; 

 its periphery is semioval. 



The angles of the jaws are furnished with many fleshy tentacles, and there 

 are apparently smaller ones on the branchiostegal membrane. 



The abdomen has a small azygous almost oblong quadrangular plate in 



[Sept. 



