1903.] [natural sciences of Philadelphia. 741 



greatest depth about midway in its length. Caudal peduncle com- 

 pressed, its least depth a little less than half its length. 



Head rather small, compressed, more or less constricted below, 

 upper profile nearly straight, and lower well curved convexly. Snout 

 long. Eye moderate, high, circular and anterior. Mouth horizontal, 

 jaws subequal or lower only slightly projecting. Upper jaw broad and 

 depressed. Teeth uniserial, bicuspid, and rather small in jaws. No 

 teeth on vomer. Tongue small, far down and little free in mouth. 

 Each ramus of mandible well elevated inside of mouth. Maxillary 

 slender, vertically inclined, and falling little short of front rim of 

 orbit. Nostrils well separated. Interorbital space rather broad and 

 slightly convex. 



Gill-opening extending forward about opposite front rim of pupil. 

 Rakers slender, rather numerous, and shorter than filaments. No 

 pseudobranchise. Isthmus narrow, trenchant. 



Scales of moderate size, cycloid, and hardly imbricated, those on 

 chest smaller and crowded. Head scaly, about three rows on cheek. 

 Bases of soft dorsal and anal with scaly sheaths. Base of caudal with 

 small scales. Several irregular or broken series of tubes on side of 

 body representing lateral system, lowest most perfect. 



Spinous dorsal inserted a little behind anus, small, much lower than 

 soft dorsal and second spine apparently largest. Soft dorsal low, 

 anterior rays highest, and inserted a little before middle of base of 

 anal. Anal large, similar in shape to soft dorsal and beginning close 

 behind anus. Caudal damaged, evidently emarginate. Pectoral 

 rather long, reaching past base of ventral, and first rays longest. Ven- 

 tral rather small. Anus nearly midway between tip of depressed ven- 

 tral and origin of anal, at least distinctly before origin of spinous dorsal. 



Color in alcohol dull brown, back a little darker. A broad silvery 

 lateral band equal to f eye-diameter, and upper half grayish. Sides 

 of head with silvery reflections. Fins plain brownish. Orbit brassy. 

 Peritoneum silvery-gray. 



Length (caudal damaged) 3^ inches. 



Type No. 10,206, A. N. S. P. Magdalena Bay, Lower California. 

 W. N. Lockington. Two examples, inclusive of type. 



This species appears to be a southern representative of Atherinops 

 aflinis (Ayres), differing in the anterior position of the vent. 



(Named for Magdalena Bay, Lower California.) 



