522 CONTEIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



(with caudal). D. X, 10 ; A. 8. L. l-^- inches. Rio Seco and Eio Leona, 

 Texas. [Glrard.) The types of this species, examined by us, have the 

 lateral line incomplete and the premaxillaries not protractile. 



{Bolcosonia gracile Girard, Proc. Acad. Nat. Sci. Phila. 1859, 103.) 



** Dorsal spines 6; anal spines obsolete? (Alvarius^ Girard.) 



§23. P. BateraSis (Grd.) J. & G. 



"A representative of the Etheostomoid family was procured by the 

 United States and Mexican Boundary Commission at the Eio Grande 

 del Norte (Eio Bravo). It constitutes 'a new generic type allied to 

 Catonotus, and to which we have applied the name of Alvarius, with the 

 following characters. Head elongated and tapering. Mouth terminal, 

 large, not protractile; lower jaw longer than the upper. Teeth very 

 minute. Opercular apparatus, cheeks, and throat scaly. First dorsal 

 nearly equal in height to the second, from which it is quite distinct. 

 Anal fin much smaller than the second dorsal ; caudal fin truncated ; 

 five soft rays to the ventrals. Ventral scales uniform." Body slender, 

 elongate. Head subconical and tapering forward. Eye equal to snout, 

 4 in head. Maxillary reaching pupil. First dorsal about equal to second 

 and separated from it. Anal smaller than second dorsal, the last rays 

 of the two fins opposite each other. Scales very small. Lateral line 

 median. Brownish, back spotted ; sides with a narrow blackish streak, 

 which extends around the snout; first dorsal with a black spot on its 

 upper posterior edge; caudal transversely barred. D. VI, 10; A. 8. L. 

 If inches. Rio Grande. (Girard.) 



(Alvarius lateralis Girard, Proc. Acad. Nat. Sci. Pbila. 1859, 101.) 



2«7.— MICSJOPEKCA Putnam. 



(Putnam, Bull. Mus. Comp. Zool. I, 1833, 4: type Microperea punctulata Tutn.) 



Body rather short, compressed. Mouth moderate, the jaws about 

 equal. Premaxillaries not protractile. Vomerine teeth present. Gill- 

 membranes scarcely connected. Scales large. Lateral line obsolete. 

 Dorsal fins small, subequal, well separated, the first with six or seven 

 spines ; anal fin much smaller than second dorsal, with two well-devel- 

 oped spines. Color greenish, with dusky markings. Size very small, 

 probably the smallest of the spiny -rayed fishes, (.'j-r/.po^, small; -epy.r], 

 perch.) 



§24. M. pFCKlaaos Hay. 

 Body short and stout. Snout conical, pointed; jaws equal; mouth 



* Alvarius Girard, Proc. Acad. Nat. Sci. Phila. 1859, 101: type Alvarius lateralis. (A 

 coined name without meaning.) 



