222 ZOOLOGY. 



Another genus of Percoids, Holocentrum, has brilliant and denticulated 

 scales, a spinous and denticulated operculum, and a preoperculum, with a 

 well developed spine, projecting posteriorly. A species, H. longipinne 

 {pi. 83, ßg. 1), is found in the American waters. The genus Sphyrcena has 

 a greatly elongated body, with two separated dorsals. Lower jaw longer 

 than upper : both with strong teeth. Ventrals posterior to the pectorals. 

 A species of this genus, a. barracuda, is found on the southern shores of 

 the United States, particularly about the Florida reefs, where it is more 

 dreaded for its ferocity than the shark. It is there called barracuda pike, 

 or barracuda, and attains a length of six or seven feet. Sphyrcena spet, a 

 Mediterranean species, is figured '\n pi. 83, ßg. 4. A species of Trachinus, 

 T. draco, sea-cat, or weever {pi. 81, ßg. 12), is much feared for the 

 injuries it can inflict with its spinous dorsal. A special regulation in 

 PVance requires that these spines be cut off before the fish is exposed to 

 sale. It has not yet been found in American waters. Acerina constitutes 

 a genus of fresh-water fish, allied to the true perches, but has a single 

 dorsal fin. Of two species, both European, A. cornua, or the ruffe, is found 

 in various waters of England and the continent. Its flesh is well esteemed, 

 but the fish never attains to a large size. Figured \n pi. 83, ßg. 10. The 

 geniis Mullus, or mullet, has two separated dorsals, and two cirri at the 

 symphysis of the lower jaw. The genus is not found in America. PI. 85, 

 ßg. 7, represents M. harhatus. 



The next family is that of the Sclerogenid.e, or TRiGLiD.E,with the head 

 spined and armed in various ways. The suborbital bone is. extended more 

 or less backwards, and articulated to the preoperculum. The genus 

 Trigla has the operculum and shoulder-plate running out backwards in a 

 spine ; seven branchiostegous rays, and three detached rays at the base of 

 each pectoral fin. Trigla lyra, or the piper {pi. 83, ßg. 7), is a rather 

 rare European species. T. cuculus occurs on the coast of the United 

 States. More American species are found in the genus Prionoius, closely 

 allied to Trigla. Dactylopterus has the detached filament of Trigla 

 greatly elongated, so as to exceed in length the fish itself, and united by a 

 fin by means of which it can be sustained in the air for a short period of 

 time. The best known species is D. volitans, or flying-fish, and is shown 

 mpl. 83, ßg. 12. There is another flying-fish, E.toc(stus, belonging to the 

 EsocidcB, which is a better flyer than Dactylopterus. The genus Cottus 

 has a variously-armed head, which is large and depressed ; teeth in both 

 jaws, and on the front of the vomer ; branchiostegous rays six; two dorsals, 

 distinct or but slightly connected, ventrals small. Two distinct types of 

 this genus exist, one with the head strongly armed with spines of various 

 kinds, and the other with the spines few in number, and nearly obsolete. 

 The latter are all fresh water, the former marine. Numerous species 

 of fresh water Cottus occur both in Europe and America, all closely 

 resembling each other. They may be distinguished geographically by the 

 fact, that while the small subcutaneous plates along the lateral line are 

 continued out to the tail in the European species, in the American they 

 cease within a short distance (one fourth, perhaps) of the total length, and 

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