382 SPINY-FINNED GROUP. 



preopercular bone is simple, but becomes branched in many of the marine forms. 

 The common fresh-water species, which ranges over Central and Northern Europe 

 to Northern Asia, seldom exceeds 4 or 5 inches in length, and is more generally 

 found in small streams than in large rivers. It has a well-known habit of con- 

 cealing its broad and flat head beneath loose stones on the river-bottom, and in 

 this position will lie motionless for hours, but when disturbed swims swiftly away. 

 Its food consists of the larvae of water-insects and crustaceans, as well as the eggs 

 and fry of other small fish. The other British representatives of the genus are 

 all marine, and include the sea-scorpion (0. scorjrius) and father-lasher (0. bubalis), 

 both of which are also found on the opposite side of the Atlantic, as well as two 

 other less common species. The males of the common marine species are stated 

 to build a nest of stones and seaweed for the reception of the spawn ; and to guard 

 and defend the young fry when hatched. 



On the Indian and Australian coasts the bull-heads are represented by the 

 so-called flat-heads, or crocodile-fishes {Platycephalus), in which the much 

 depressed head is more or less fully armed with spines, and the body covered 

 with ctenoid scales ; the anterior spine of the first dorsal fin being isolated from 

 the rest, and teeth present on both the vomer and palatine bones. Day writes of 

 these fishes that " the wounds from their spines are dreaded because of the violent 

 irritation they occasion. Their eyes are peculiar; the iris possesses two semi- 

 circular flaps, one above, the other below, the upper being usualty the larger ; 

 these flaps can be brought close together, probably under the stimulus of light." 



Of a decidedly ugly appearance, the gurnards (Trigla) are easily 

 recognised by their enormous, square, and elevated heads, in which 

 the upper surface and sides are entirely bony, and likewise by the finger-like 

 first three rays of the pectoral fins, which serve not only for walking on the 

 sea-bottom but likewise as organs of touch. There are two dorsal fins, of which the 

 spinous is tall, and the soft one long, low, and similar to the anal ; the tail-fin 

 being slightly rounded. The teeth are villiform ; and the air-bladder, which is 

 generally furnished with lateral muscles, may be divided into two longitudinal 

 halves. They have been divided into three subgenera, of which the typical one 

 is characterised by the absence of teeth on the palatines, and the small size of the 

 scales, with the exception of the highly modified ones forming the lateral line, 

 which are large, triangular, and spiny. The second group is distinguished by the 

 medium size of the scales; while in the third teeth are present on the palatine 

 bones. Their colours are frequently brilliant, and the fins highly decorated. 

 The genus is represented by some forty species, distributed over all temperate and 

 tropical seas, out of which no less than seven are found in British waters. Their 

 flesh, which is firm and flaky, and of a pale orange-pink tinge, is extensively used 

 as food. One of the best known of the British species is the red gurnard (T. pini), 

 which seldom exceeds 12 or 14 inches in length, and, when freshly caught, is of 

 a bright red colour, with the sides and under-parts silvery white, and the fins 

 reddish white. Its food consists of crustaceans, which give the pinkish tinge to 

 its flesh, and the spawning-season is May or June. The sapphirine gurnard 

 (T. hirimdo), which is the one represented in the woodcut, is another British 

 species, taking its Latin name from the length of the pectoral fins, and its English 



