FAMILY, I— PERCnm 71 



third of the orbit. Preorbital very finely serrated on its lower edge in the adult but more distinctly in the 

 young. Preopercle nearly evenly serrated, most coarsely at its angle : sub- and inter-opereles entire, in 

 some of the youug they are rough or even serrated at their approximating edges. Lower opercular spine the 

 longer, about 2/3 as long as the orbit, but not equalling the length of T. jarbua. Teeth — villiform in the jaws, 

 with an outer somewhat enlarged row : deciduous ones present in the young on the vomer and said also to 

 exist on the palate. Shoulder-bone serrated, and two or three strong spines on the bone at the axilla. Fins — 

 dorsal spines moderately strong, the fourth slightly the longest and equal to half the height of the body below 

 it, their length decreases to the last but one, which is only two-thirds or three-fourths as high as the last : 

 second anal spine the strongest, but rather shorter than the third : caudal emarginate. Scales — above the 

 lateral-line a little smaller than those below it. ' Colours — silvery, with four horizontal blackish-brown lines, 

 the first from the second to the last dorsal spine leaving a narrow yellow intervening space between them : the 

 second from the nape to the last few dorsal rays, and ending by being continued on to the fin as well as joining 

 the line below it : the third (which is often the last) from the snout to upper part of the tail : the lowest (often 

 absent) from the base of the pectoral to the lower caudal lobe. Dorsal fin with a black blotch between its 

 third and its seventh spines, and a dark band along the upper portion of the rays. An horizontal black band 

 along the first half of the anal fin. Caudal with two oblique bands across its lower lobe, and two also across 

 its upper, the superior of which is interrupted in the adult, the lobe has likewise a black tip. 



In the young the colours are much darker, and due to innumerable fine brown spots they appear as if 

 they were dark with two light bands only half the width of the darker ones. The anal fin has two large black 

 spots, one on the interspinous membrane and continued on to the first three rays : the second is confined to the 

 last three rays. A large black shoulder spot is sometimes visible. There are teeth on the vomer. 



Variety. — In a small specimen from Madras, 2-L inches long, there are D. y, the two first spines 

 apparently being absent, it is otherwise identical with the young of this species. 



Thereupon cinereus (Cuv. and Val.) Giinther in the British Museum is this species, in which the bands, 

 though very faint, may still be traced : as the condition of the specimen is good, either it must have been 

 somewhat of an albino variety, or else it has been kept in such a light that etiolation has resulted. 



Habitat. — East coast of Africa, seas of India, through the Malay Archipelago to China, attaining at least 

 six inches in length. 



Genus, 15 — Datnia, Cuv. and Vol. 



Mesopristis, sp. Bleeker. 



Branchiostegals six : pseudobranchim. Body elevated, with a somewhat rectangular or concave profile : snout 

 pointed and somewhat produced. Eyes of moderate size. Opercle with spines : preopercle serrated. Teeth villiform 

 in both jaios : palate edentulous. Dorsal fin single, bid slightly notched, spines strong (12-13) and occupying a 

 considerable amount of the length of the fin: anal with three spines. Scales of moderate size. 



SYNOPSIS OF INDIVIDUAL SPECIES. 



1. Datnia argentea, D. ~^, A. f, L. I. 56. Second anal spine strong. Seas of India to the Malay 

 Archipelago. 



Datnia argentea, Plate XVIII, fig. 7. 



Bahiia argentea. Cuv. and Val. iii, p. 139, pi. 54 ; Bleeker, Perc. p. 52. 



Mesopristis macr -acanthus, Bleeker, fiatavia, p. 523. 



Datnia cancelloides, Bleeker, Sumatra, p. 247 (young). 



Therapon argentews, Giinther, Catal. i, p. 283. 



Thereupon (Datnia) argenteus, Bleeker, Therapons, 1872, p. 382 (not Kner.) 



B. vi, D. \%, P. 14, V. 1/5, A. f, C. 17, L. 1. 56, L. tr. 30-35, Case, pyl. 11. 



Length of head 1/4, of caudal 1/5, height of body 1/3 to 3j in the total length. Eyes — diameter 1/4 of 

 length of head, lj diameters from end of snout, and 4/5 of a diameter apart. The maxilla does not quite 

 extend to beneath the anterior edge of the orbit. Snout pointed. Preorbital serrated along the last half of 

 its lower edge. Preopercle serrated along its vertical margin. Teeth — villiform in jaws, none on the palate. 

 Fins — fourth and fifth dorsal spines the longest and rather more than half the height of the body : second anal 

 spine very strong, longer than the third, and exceeding the length of the longest in the dorsal fin : caudal 

 notched. Colours — silvery, darkest along the back : a narrow black outer edge to the dorsal fin : a band along 

 the middle of the anal, which also has a dark margin. 



The young appear to have longitudinal bands. 



As Cuvier observes, this fish has a more elevated body than in the typical Tlierajwns, a somewhat concave 

 profile, and pointed snout, the dorsal spines being stronger and their bases occupying a comparatively greater 

 extent of the back than the rays, and there being a very slight notch between the last two. In fact it is his 

 first species of Datnia, a genus which some Ichthyologists consider ought not to be retained. 



Habitat. — Cape seas, seas of India to the Malay Archipelago and beyond. I never obtained it in India, 

 saw it in a local collection there, or observed any figure of it amongst drawings of Indian fishes, but as it is 

 found in the Malay Archipelago, stray ones may very possibly be occasionally captured on the coast of India. 



