THE GENUS MOXACASTHUS. 49 



dorsal spine locks into the first One of the most remarkable characters of the genus is a soft smooth 

 furrow in front of the eye. There are shields behind the small gill-openings, and the face is usually 

 covered with scales similar to those which exist on the body. There are no spines or tubercles on 

 the tail. Thirty-two scales extend between the dorsal fin and the vent. The ventral spine is movable. 

 Dried specimens are always brown, but Yarrell records that the living fish is turgid blue. An adult 

 specimen has a length of fourteen inches ; young specimens are sometimes marked with dark-brown 

 spots. Some of the Eastern species, like the Batistes niger and Batistes bursa, have a series of 



OSTRACION QI'ADRICORNIS. 



recurved spines on the tail. Other species, like the West Indian Batistes ringens, have longitudinal 

 grooves on the cheeks. Several species have no groove in front of the eye, while the Batistes 

 erythrodon has the teeth of a reddish-brown colour. 



The genus Monacanthus has the body covered with very small rough scales. The ventral fin is 

 usually fixed ; the first dorsal fin is a single strong spine with a rudimentary spine behind it. In the 

 Mdnacanthus peronii, and some other Australian species, the dorsal spine has four edges, which are at 

 equal distances from each other, and each is barbed. In this species the spine is inserted above the 

 middle of the orbit. The third group of the Sclerodermi contains only the Ostracion, which, however, 

 is represented by about twenty-two species. These fishes are contained in a carapace formed of 

 hexagonal plates which touch each other, but the snout, bases of the fins, and hinder part of the tail 

 are covered with soft skin. The ventral fins do not exist. The maxillary and pre-maxillary bones 

 have become blended together, and the jaw carries a single series of small teeth. There are only 

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