The jaws, the uneven lobate disk of the preoperculum and the branchiostegous membrane are naked, the rest of them being scaly.  The scales of the cheek are disposed in six concentric curves, the same arrangement extending to the gill-cover, but less conspicuously.  A small flat spinous point projects beyond the scales of the operculum, which has a very narrow membranous edging.  The scales are ciliated.  The caudal is slightly notched at the end, its basal half is scaly, as is also the base of the pectorals; the rest of the fins are scaleless.  The dorsal is nearly even, its height being, however, rather greatest at the fourth or fifth spine.  Its end is rounded.

A dark stripe, commencing at the top of the snout, runs through the eye straight to the tail, and a fainter one occupies the summit of the back to the end of the dorsal.  The curve of the lateral line rises above the lower stripe anteriorly, but coincides with it beyond the posterior end of the dorsal.  The rest of the fish is silvery, and the fins are not marked.  These colours are described from a specimen preserved in spirits.  Length, 5 inches.

HABITAT.  King George’s Sound. (Bynoe).

...

Chelmon marginalis.  RICHARDSON.

Chelmon marginalis, Richardson, Annals and Mag. of Nat.  Hist. 10, page 28, September 1842.

RADII.  D.9 :  31; A. 3-2l; C. 17 3/3; P. 16; V. 1 :  5.

FISHES.  PLATE 4.  Natural size.

This fish is described in the Annals of Natural History from a dried specimen brought from Port Essington by Mr. Gilbert.  It has very much the form of Chelmon rostratus, but wants the eye-like spot on the dorsal.  Several examples in spirits were brought by the officers of the Beagle from the north-west coast of Australia, all of which show a broad band passing between the dorsal and anal fins, which was not visible in the dried specimen.  This band is bounded anteriorly by one, and posteriorly by two whitish lines.  In the Annals the anal fin is described as being more angular than the dorsal, but in the specimens in spirits the reverse appears to be the case.  This variation depends on the degree or expansion of the fins, and both may be much rounded by pulling the rays apart.  The exact distribution of the bands may be clearly made out from the figure, which is very correct.  The rays of the fins probably vary in number in different individuals, and our careful enumeration of those specimens kept in spirits, as recorded above, gives two or three soft rays more in the dorsal and anal, than we were able to detect in the dried skin.  Length, 5 1/4 inches.

HABITAT.  Northern and north-western coasts of Australia.

...

ASSICULUS.

CH.  GEN.  Corpus compressissimum, assulaeforme:  caput crassius, minus altum, declive.  Os parvum.  Maxilla inferior porifera, ore clauso ascendens, hinc, ore hiante, ultra maxillam speriorem modice protractam extensa.