SCLERODERMI. 267 



Order V— PLECTOGNATHI. 



Teleostean fishes, with an incompletely ossified skeleton and few vertebrae. 

 Gill-openings narrow, situated in front of the pectoral fins : gills pectinate. 

 Mouth narrow: the bones of the upper jaw mostly united, and sometimes 

 produced into a beak-like form. Teeth may be distinct in the jaws, or absent. 

 There may be a single soft-rayed dorsal fin belonging to the caudal portion of the 

 body and placed opposite the anal : while in some a spinous dorsal is likewise 

 present : ventrals may exist, in the form of spines. Skin smooth, with rough 

 scales, or ossified in the form of plates or spines. Air-bladder without any 

 pneumatic duct. 



Geographical distribution. — Mostly oceanic, but some are found in large 

 rivers and many in estuaries and tidal pieces of water in temperate and tropical 

 portions of the globe. They are only seen as occasional wanderers to our shores. 



Synopsis of Families. 



1. Sclerodermi — Distinct teeth in the jaws. 



2. Gymnodontes — Jaws modified into a beak. 



Family I— SCLERODERMI. 



Body compressed or angular : snout somewhat produced. Distinct teeth in 

 small numbers in the jaws. A barbel in one genus. A spinous dorsal and 

 ventral fins generally present but variously modified. Skin rough or spinate, or 

 the scales in the form of a firm carapace. 



Genus I — Balistes, sp. Artedi. 



Balistapus, Tiles. Xenodon, Erythrodon and Pyrodon, Ruppell. Melichthys and 

 Leiurns, Swainson. Sub-genera Parabalistes, Pseudobalistes and Ganthidermis, 

 Bleeker. 



Branch iostegals six. Body compressed. Barbels absent. Sometimes a groove 

 before the eyes. Upper jaw with a double roio of incisor -like teeth, 8 in the outer 

 and 6 in the inner row : mandibles %oith 8 similar teeth in one row : these teeth may 

 be white, uneven, and more or less notched (Balistes) : or white, even, and incisor- 

 like (Melichthys) : or of a burnt sienna colour, with the supero-lateral pair pro- 

 jecting (Erythrodon). The first dorsal fin consisting of a strong spine, succeeded by 

 two weak ones : ventrals as an osseous appendage. There may or may not be oval, 

 flattened, osseous productions behind the gill-openings. Scales forming a carapace: 

 in some species there are roivs of spines or tubercles on the side of the free portion of 

 the tail, which is either compressed or depressed. 



Eating the flesh of these fishes occasions at times symptoms of the most 

 virulent poisoning. Dr. Mennier, at the Mauritius, considered that the poisonous 

 flesh acted first on the nervous tissue of the stomach occasioning virulent spasms 

 of that organ, and shortly afterwards of all the muscles of the body. The frame 

 soon becomes racked with spasms, the tongue thickened, the eye fixed, the 

 breathing laborious and the patient expires in a paroxysm of extreme suffering. 

 The first remedy should be a strong emetic, and subsequently oils and demulcants 

 to allay irritability. 



The two forms which are said to have been taken in our isles are : 



1. Balistes maculatus — D. 3/26-27, A. 24-25, L. 1. 46-55: no osseous plates 

 behind the gill-openings. 



2. Balistes capriscus — D. 3/28, A. 24-25, L. 1. 52-62. Osseous plates behind 

 the gill-opening. 



1. Balistes maculatus, Plate CXLV. 



Guaperva longa, Willugh. Append, p. 21, t. 120. Sabaco, Parra, p. 17, 

 lam. 10. 



