274 Transactions. — Zoology. 



toothless ; patch on vomer. Operculuui spiuiferous, smooth ; 

 proeopercukun finely serrated. Branchiostegals, 6. Dorsal re- 

 ceived mto a sheath, notched, with 12 spiny unequal, and 11 

 soft, rays ; anal with 3 spiny and 9 soft rays. Scales quadrila- 

 teral, -foin. Caudal deeply forked. Air-hladder simple. Cffica 

 pylorica (9) few. 



Plagiogeneiou is thus separated by its vertical mouth from 

 the following genera : Therapon, 2Iacquaria, Prist ijiovia, Hamu- 

 lon, Hapalogcmjs, Diagramma, Scoloj^sis, Dcntcx, Synagris, 

 Pcntajnis ; and by its simple air-bladder from Helotes, Cono- 

 don, Mceua, and Smaris ; by its dorsal-fin formula from Hy- 

 2Jcrogly2)iie, Gerres, Pristipomoicies, CU(etoi)terus, Apharcus, 

 Cceslo, Erythrichthys, Pcntaprion, and Polycentrus ; and by 

 the form of its body from Lohotes (differentiated also by its 

 pseudo-branchiae) and Datnioides (also distinguished by the 

 shape of its caudal fin). 



Plagiogeneiou rubiginosus, Hutton. 



D., i-i- ; A., -^-^ ; L. lat. 81, L. trans. 13/25. 



General colour pink-red ; above the dorsal line, and for 2 

 to 3^ scales below it, the colour is grey washed with pink-red, 

 in consequence of a wide band on each scale of grey, margined 

 with pink-red. The whole surface below the grey belt is deep 

 salmon-pink. Each scale has a metallic purple spot, which 

 falls into longitudinal lines of purple along the sides. The 

 purple is replaced by deeper pink on the ventral surface be- 

 tween the ventral and anal fins. On the margins of the 

 opercula the colour is nacreous purple ; in front of the eye, 

 and the whole of the maxillary bone and lower mandibles, are 

 of a rich purplish-pink nacreous colour. The length is three 

 times the height of the body, or four times the length of the 

 head. The diameter of the eye goes three and a half times 

 into the length of the head. Scales ctenoid, ^^ of an inch 

 across, and quadrilateral in shape, with semicircular anterior 

 margin. 



Body compressed, the greatest height under the third dorsal 

 spine. Mouth small, vertical, protrusive. Series of very minute 

 teeth in each jaw^ ; palate toothless. Vomer with a patch of 

 teeth. Praeoperculum slightly denticulated on its lower margin, 

 smooth below ; operculum smooth, armed with two small fiat 

 spines. Dorsal single, deeply notched ; the fourth spine, which 

 is the longest, goes nearly 2^ times into the length of the head. 

 Spines of the dorsal and anal fin very strong. Anal and soft 

 dorsal not covered with scales ; the fins are received into a 

 sheath, which is covered with fine scales; the spiny parts 

 scaleless. Caudals and exteriors of pectorals and ventrals 

 partly covered with scales. Caudal forked, each lobe about 

 equal to the length of the head. The dorsal commences at the 



