ii2 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. VII. 



Color uniform, bright silvery, back darker. 



I did not see or secure any specimens of this species. So far as 

 I could learn, it is not taken in Lake Managua, and is not abundant 

 in Lake Nicaragua. This species is known as Sabalo. The same 

 name is also used for Brycon dentex. This species is said by the 

 natives to grow to a greater length than the height of a man. 



Family Dorosomidre. 

 Genus Dorosoma Rafinesque. 



Dorosoma chavesi sp. nov. SABALO. 



Type, No. 5928, F. M. N. H.; length, 170 mm. ; Lagoon Jenicero, 

 Granada, Nicaragua. 



Opisthonema libertatis Gill, Proc. Acad. Nat. Sci., Phila., 1877, 

 187, Lake Nicaragua (nee Giinther). 



Head 2.7 to 3.1; depth 2.8; D. 12 to 15; A. 26 to 30; scales 

 74 to 78; scutes 17 to 19-9 to 10. Body elongate, compressed, the 

 ventral outline more curved than the dorsal; head large; mouth 

 large, the jaws subequal; maxillary very long and slender, its tip 

 reaching vertical from middle of eye, without distinct notch on its 

 outer margin, its length 3 to 3.3 in head; supplemental maxillary 

 bone slender; mandible strong, its length 2.1 in head; eye large, with 

 well-developed adipose eyelid, its diameter 3. to 3.3 in head; origin of 

 dorsal fin nearer base of caudal than tip of snout; last ray of dorsal 

 slightly produced in most individuals but seldom reaching half-way to 

 base of caudal fin ; tips of ventrals reaching slightly past base of ven- 

 trals; base of anal shorter than head, its length i.i to 1.5 in length of 

 head ; scales persistent. 



Color steel-blue above, silvery below; a black humeral spot; fins 

 all plain. 



This species differs from other known members of the genus in the 

 larger head, longer and more slender maxillary and premaxillary, and 

 having base of anal fin shorter than the head. Named for Senor Don 

 Dioclesiano Chaves, of the National Museum of Nicaragua. 



Momotomba (15), 47 to 80 mm.; Managua (35), 60 to 180 mm.; 

 San Francisco (6), 145 to 165 mm.; Jenicero (20), 160 to 210 mm. 



Family Pceciliidae. 



Of this family there are but two genera so far known to occur in 

 the lake. 



