420 CALIFORNIA ACADEMY OF SCIENCES. 48 
pectoral 1% longer than head, 3% in body; caudal 
slightly longer than head: interorbital space broad, nearly 
equal to eye. 
Body much compressed, the belly sharp edged, con- 
cave on each side below pectorals, as if pinched together 
between the fingers, the ribs reaching the edge, the scales 
passing around it; the edge almost carinate. Back 
narrow. Scales smooth, none on dorsalor anal. Mouth 
small, terminal, the short jaws curved, the structure pre- 
cisely as in J7enzdia, the teeth moderate, curved, those in 
the upper jaw longer; opercles oblique behind, not ver- 
tically truncate. Gill-rakers numerous, long and slender. 
Pectorals very long and falcate, reaching to front of anal 
and beyond tips of the short ventrals, their posterior mar- 
gin concave: spinous dorsal small, inserted midway be- 
tween edge of preopercle and base of caudal, about over 
sixth ray of anal; last ray of dorsal considerably before 
last of anal; base of anal 1% times length of head, 234 
in body. 
Color, light green, much dotted above, translucent be- 
low; a black streak of dots along base of anal; some on 
sides of head; median line of back dusky; fins all pale; 
no black on spinous dorsal, ventral or pectoral; lateral 
stripe % width of eye, underlaid by black: a large, per- 
fectly transparent, space above front of anal, marking 
the posterior portion of the air-bladder. 
Length, 2% to 3 inches. Rather common in the estu- 
ary at Mazatlan. 
About twelve specimens obtained, numbered 2688 in 
the Ls So: Jc Univ. Mis. 
64. Thyrina crystallina Jordan & Culver, n. sp. 
Rather common in the Rio Presidio in fresh water; not 
seen elsewhere. It is apparently not found in the sea, 
but confined to fresh or brackish waters. 
