XEXATHEEITSiA.— MUGILID.E. 65 



of small scales. Dorsal III-V, I 8-9 ; origin of spinous dorsal above or a little behind that of the anal. 

 Anal I 19-21. Pectoral asymmetrical, pointed, 4 the length of head, extending to above the middle of 

 ventrals. Caudal forked. Caudal peduncle twice as long as deep. 



Hah. Mexico, Puo Papaloapam : 

 Eefugio 1, El Hule i. 



Here described from five specimens, measuring up to 55 mm. in total length, from 

 Refugio {Meek). 



Fam. 2. MUGILID^. 



The Mugilidae are closely related to the Atherinidte and have the same wide 

 distribution. Most of the species of Mugil and allied genera with ciliiform teeth are 

 marine, but freely enter fresh water. Agonostomus and Jotnrus comprise tropical 

 fresh-water fishes, especially abundant in mountain-streams. 



The Mexican and Central-American Mugilidse have the following features in 

 common : — Body elongate, more or less compressed, covered with rather large scales, 

 which extend on to the upper surface of the head. Lateral line usually absent, never 

 complete. Two well-separated dorsal fins, the first formed of 4 rather strong spines, 

 the second of a spine and 7 to 10 articulated rays. Anal with 2 or 3 spines and 

 7 to 11 articulated rays. Pectorals placed high ; ventrals abdominal, each with one 

 spine and 5 branched rays. Caudal forked. Prasmaxillaries protractile ; jaws with 

 teeth, which may be either well-developed or vestigial; palate with or without teeth. 

 Coloration silvery, the back greenish or olivaceous ; sometimes dark longitudinal 

 stripes along the series of scales. 



Synopsis of the Mexican and Central-American Genera. 



I. Bands of small fixed teeth in the jaws and on the palate. 



Teeth in the jaws pointed 1. Agonostomus. 



Teeth in the jaws incisor-like, with serrated edges 2. Joturus. 



II. Teeth in the jaws small, in one or more series ; palate toothless. 



A. Teeth ciliiform, in one or a few series j lips not very thick; ranai of lower jaw meeting at 



an angle which is not very acute. 



Three anal spines 3. Mugil. 



Two anal spines 4. Querimana. 



B. Teeth in several oblique series ; lips thick ; rami of lower jaw 



meeting at an acute angle 5. Ch^nomugil. 



I have given full descriptions of the Mexican and Central-American species of the 

 genera Agonostomus and Joturus, which appear to be true fresh-water fishes, and for 

 purposes of comparison I have included in my account of the former genus two species, 

 A. percoides and A. microps, which are at present known only from specimens in the 



BIOL. CENTR.-AMEK., Pisces, May 1907. K 



