604 FISHES. 



backwaters on the shore, in whicli they rapidly grow to a 

 marketable size. Several species are more or less abundant 

 on the British coasts, as Mugil octo-radiatus (Fig. 105, p. 254), 

 M. capita, M. auratus (Fig. 106, p. 254), and M. septentrionalis 

 (Fig. 107, p. 254), which, with the aid of the accompanying 

 iigures, and by counting the rays of the anal fin, may be 

 readily distinguished — M. octo-radiatus having eight, and M. 

 capita and M. ccwratus nine soft rays. A species inhabiting 

 fresh waters of Central America (M. proboscideus) has the snout 

 poiated and fleshy, thus approaching certain other fresh- 

 water and littoral Mullets, which, on account of a modifica- 

 tion of the structure of the mouth, have been formed into a 

 distinct genus, Aganastoma. Myxus comprises Mullets with 

 teeth more distinct than in the typical species. 



This genus existed in the tertiary epoch, remains of a 

 species having been found in the gypsum of Aix, in Provence. 



Twelfth Division — Acanthopteeygii Gasteosteifoemes. 



The spinous dorsal is composed of isolated spines if present ; 

 the ventrals are either thoracic or have an abdominal position 

 in consequence of the prolongation of the pubic banes which are 

 attached to the humeral arch. Mouth small, at the end of the 

 snout which is generally more or less produced. 



First Family — Gasteosteid^e. 



Body elongate, compressed. Cleft of the mouth oblique; 

 villiform teeth in the jaws. Opercular bones not armed ; in- 

 fraorbitcds covering the cheek; parts of the skeleton forming 

 incomplete external mails. Scales none, but generally large 

 scutes along the side. Isolated spines in front of the soft dorsal 

 fin. Ventral fins abdominal, joined to the pubic bone, com- 

 posed of a spine and a small ray. Branchiostegals three. 



