708 PLECTOGNATHI. 



RhyncJiotus margaritatus (Bibron) Dumeril. Rev. Zool. 1855, p. 282. 



Tropidichthys margaritatus and Beiinetti, Bleeker, Amboina, pp. 500, 504. 



Anosmius Bennetti and margaritatus, Bleeker, en. Pise. pp. 202, 203. 



Psilonotus Bennetti, Bleeker, Ternate, p. 230, and Sumatra, p. G6. 



Canthogaster ocellatus and margaritatus, Bleeker, Atl. Ich. v, pp. 80, 81. 



Tsilonotus ocellatus and margaritatus, Bleeker, Atl. Icb. v, t. ccsiv, f. 4, and t. ccxiii, f. 5. 



B. V, D. 9-10, P. 14-16, A. 9, C. 11. 



Tjength of bead equal to its distance from tbe base of the dorsal fin. Eyes — rather high up and in the 

 posterior half of the length of the head. Upper profile of snout rather concave. Fins — dorsal situated in 

 almost the last fourth of the total length excluding the caudal fin, which last is rather convex and from 4s to 

 5 in the total length. Spines — minute, and generally covering the entire body, but occasionally deficient from 

 the caudal portion. Colours — of a dull reddisli, becoming light beneath, fins yellow. The body is variously 

 marked : in T. margaritatus, there is a black blue-edged ocellus on either side of the dorsal fin : horizontal blue 

 lines round the eye and on the posterior portion of the body, elsewhere there are small yellow dark-edged 

 ocelli, which are even on the caudal fin. In T. papua the black dorsal spot is ahso present : the oblique bands 

 on the snout become nearly horizontal and a blue band passes to the vent : also angular bands on the tail : body 

 and cheeks covered with small blue, black-edged spots. In T. Bennetti, a black dorsal spot also exists. Bluish 

 vertical bands on snout and one along the middle of the throat : angular bands on the tail. Bluish spots 

 on the body, smallest on the sides of the head. 



A very good figure of this species exists amongst Sir W. Elliot's di-awings of Madras fish, which is 

 referred to by Jerdon as " Karoom palasi, Tamil. Not common at Madras." (M. J. L. and Se. 1851, p. 150.) 



Habitat. — Red Sea, East coast of Africa, seas of India to the Malay Archipelago, and beyond. 



B. — Jaws without any median suture. 



Genus — DiODON (Linnaeus) , Cuvier. 



Paradiodon, Bleeker. 



Body nearly globular. Jaws without median suture. Nasal tentacle simple, tuith a pair of lateral openings. 

 Body covered with stiff and erectile dermal spines, each having a pair of lateral roots. A portion of the oesophagus 

 dilatable, and can be distended with air. No pelvic bones. Air-vessel present. 



Geographical Distribution. — Tropical Seas to the Cape of Good Hojje. 



In the Museum at Calcutta were two examples, but without labels, of the Biodon spinosissimus ; and as 

 the British Museum contains a specimen from Siam, it is not unlikely that it is found in the seas of India. 

 The D. novemmaculatus, Bleeker, is also probably a visitor to India. 



SYNOPSIS OF INDIVIDUAL SPECIES. 



1. Biodon hystrix. Body covered with short spines, longest on the sides and behind the pectoral fins. 

 Numerous blue or brown round spots. Tropical seas. 



1. Diodon hystrix, Plate CLXXIX, fig. 4. 



Hystrix piscis, Clusius, Exot. vi, c. 23 ; Jonston, Nat. Hist. Pise. t. xlv, f. 4 ; Willugh. Hist. Pise. t. i, f. 5. 



Beversus Jndicus, Aldrov. Pise, iii, p. 113, t. sv, f. 12 ; Jonstou, 1. c. t. iii, f. 1. 



Biodon hystrix, Linn. Syst. Nat. i, p. 413 ; Bris. Barnev. Rev. Zool. 1846, p. 141, Bloch, t. cxxvi ; 

 Jerdon. M. J. Lit. and Soc. 1851, p. 150 ; Giinther, Catal. viii, p. 306 ; Klunz. Fische Roth. Mcer. 1871, p. 647. 



Biodon atringa, Bloch, t. cxxv ; Bl. Schn. p. 511 ; Lacep. i. t. xxv, f. 3 and ii, pp. 1, 3 ; Riipp. Sench. 

 Mus. Fische, p. 35 : Kaup, Wiegm. Arch. 1855, p. 227 (not Linn.) ; Bleeker, En. Pise. p. 203. 



Biodon plumieri, Lacep. i, t. iii, f. 3 and ii, pp. 1, 10. 



Biodon brachiatus, Bl. Schn. p. 513. 



Biodon piunctatus, Cuvier, Mem. Mus. Hist. Nat. iv, p. 132 ; Bleeker, Blootk. p. 19. 



Holocanthus hystrix, Gronov. ed. Gray, p. 27. 



Paradiodon hystrix, Bleeker, Atl. Ich. v, p. 56, t. ccvii, f, 2. 



Moollu plachay, Tamil. 



Body covered with coarse spines, which are longest on the sides of the body behind the pectoral fin, 

 where they become about 3/4 the length of that fin : they are dilated at their bases and usually with a pair of 

 basal grooves. Two or three pairs of immovable spines at the upper and lower sides of the tail. Colours— the 

 whole of the fish (except the ventral surface) of a light brown covered with round blue or brown spots, rarely 

 above one to the base of a single spine. The fins similarly spotted. 



Habitat. — From the Red Sea through the seas of India to the Malay Archipelago and the Pacific. The 

 example figured (11 inches in length) was brought from the Andamans by J. Wood-Mason, Esq., of the 

 Calcutta Museum. This fish attains a large size: one in the British Museum is 2| feet iu length. 



