736 PROCEEDINGS OF THE ACADEMY OF [NoV., 



THYRINA Jordan and Culver. 

 Contr. Hopkins Lab. Biol., I, 1S95, p. 419 {etcrmanni). 

 Thyrina guatemalensis (Giinther). Plate XLIII (lower figure). 



Atherinichthys guatemalensis Giinther, Proc. Zool. Soc. Lond., 1804, p. 151. 



Lakes of Huamuchal. (Mr. Salvin.) Giinther, Trans. Zool. Soc. 



Lond., 1868, p. 443. [Same examples.] 

 Chirostoma guatemalensis Gill and Bransford, Proc. Acad. Nat. Sci. Phila., 



1877, p. 187. Lake Nicaragua. [No description.] 

 Menidia guatemalensis Jordan and Evermann, Bull. U. S. Nat. Mus. (Fish 



N. Mid. Amer.) No. 47, I, 1896, p. 801. [Copied.] 

 Thyrina guatemalensis Jordan and Evermann, Rep. U. S. Fish Com., 1896, 



p. 332. [Reference.] 



Head 4i; depth 4^; D. IV-I, 9; A. I, 22; P. i, I, 12; V. I, 5; scales 

 40 to base of caudal; 27 before spinous dorsal; 8 in transverse series 

 between origin of anal and spinous dorsal; width of head If in its 

 length; depth of head 1^; snout 3|; eye 2f ; maxillary 3; mandible 

 3; interorbital space 3^; length of spinous dorsal 3; first dorsal ray 

 2 ; first anal ray 1^ ; pectoral 1 ; ventral 2 ; least depth of caudal pe- 

 duncle 2f ; length of base of anal a little less than ^ of length of body. 



Body elongate, strongly compressed, greatest depth at origin of 

 anal, and lower profile forming obtuse angle at this point. Upper 

 profile evenly convex. Abdomen strongly compressed, and edge not 

 sharp or trenchant, but rather narrowly convex. Greatest width of 

 trunk a little less than that of head, and found at bases of pectorals. 



Head elongate, conic, rather obtuse in front, sides compressed and 

 constricted below. Snout broad, and flattened above. Eye large, 

 anterior, and close to upper profile. Mouth small, oblique, and su- 

 periorly terminal. Jaws nearly equal when closed, and premaxillaries 

 protractile. Maxillary slender, and reaching posteriorly below front 

 edge of eye. Teeth rather large, conic, sharp-pointed, and biserial 

 in jaws. No teeth on vomer and palatines. Tongue small, rather 

 narrow, and free in front. Each ramus of mandible elevated inside 

 of mouth. Lips thin. Anterior nostrils lateral, about midway be- 

 tween tip of snout and orbit, posterior above front rim of orbit. Inter- 

 orbital space flat. Top of head posterior to eyes, convex. Top of 

 snout somewhat cavernous. 



Gill-opening extending forward about opposite first f of eye. Rakers 

 long, slender, and numerous. Filaments numerous, and long. No 

 pseudobranchiffi. Isthmus narrow, constricted and trenchant. 



Scales large, rather thin, cycloid, with uneven margins, and some- 

 what imbricated on side of trunk. Scales of head extending on inter- 

 orbital space where they become enlarged. Single row of large scales 

 on cheek. Scales on sides of head above, large. Snout and jaws naked. 



