88 " THETIS " SCIENTIFIC RESULTS. 



In iny specimen, well preserved in formol, the anterior profile 

 is vertical and the lower pair of canine teeth is ill-developed. 

 The two portions of the spinous dorsal are connected by a low 

 membrane ; the species thus enters the genus Novacula as 

 restricted by Gill, or the HemijHeronotus of Bleeker. 



The following is a description of the " Thetis " example : — 



D. ii. vii. 12. A. iii. 12. P. 13. V. i. 5. C. 15. L. lat 22 + 6. 



L. tr. 3/11. 



Length of head 3-2, height of body 2 45 in total length (caudal 

 excluded) ; the eye has a pronounced fleshy margin and is 5'2 in 

 the length of the head ; pectoral 12, and caudal rays 2*0 in the 

 same. 



From in front of the eye to the mouth, the profile of the head 

 is almost perpendicular ; passing upwards and backwards with a 

 sweeping curve, the highest point of the body is attained at the 

 Ijase of the third spine ; the dorsal profile is at first gently, after- 

 wards more pronouncedly, convex to the end of the dorsal fin, 

 whence it passes obliquely to the caudal rays. The ventral 

 profile forms a more even but similar convexity. The height of 

 the caudal peduncle is slightly more than its length behind the 

 last dorsal ray. 



The jaws are equal and the cleft of the mouth one-half longer 

 than the diameter of the eye, and does not reach to its anterior 

 margin. In front of the upper jaw is a pair of curved and divergent 

 canine teeth directed somewhat forward. In the lower jaw is 

 also a pair of canines ; these are very short, close together, and 

 bite between the upper ones. Behind the canine in each ramus 

 of both jaws is a series of conical teeth to the number of eight 

 or nine. 



Nasal apertures very small, rather close together, the anterior 

 with a low skinny rim nearer the eye than the edge of the snout, 

 the posterior a horizontal fissure on a higher level. On the 

 head are some scattered pores, the position of which are indicated 

 in the accompanying figure. The anterior profile of the head 

 forms a sharp keel, whose extent is circumscribed by a closely set 

 series of shallow horizontal grooves. The eye is surrounded by a 

 membrane which is widest above and below the posterior angles, 

 where it is free behind. 



The first dorsal spine is planted slightly behind the centre of the 

 ej'^e, and is a little shorter than the second, which is 2 35 times in the 

 length of the head. This spine is remote fi-oin the third, but attached 

 by a low membrane. The remaining spinous portion is low, but 

 the rayed })art uniformly increases in height, and the last rays, 

 which are longer than the second spine, extend to the base of the 



