1911.] NATURAL SCIENCES OF PHILADELPHIA. 519 



upper branch of 1. 1. usually 16, sometimes 17; scales in lower branch 

 of 1: 1. 7 to 10 to caudal base, and 2 more on latter (with tubes); 

 4 scales above upper branch of 1. 1. to spinous dorsal origin; 5 scales 

 below lower branch of 1. 1. to spinous anal origin; usually 9 predorsal 

 scales, sometimes 8; left gill-rakers 2 + usually 9, sometimes 10; 

 right gill-rakers usually 2, sometimes 3 + usually 9, sometimes 10; 

 snout 2 to 3 in head; eye 3f- to 4|; maxillary 3f to 4; interorbital 

 2| to 3 ; length 2h to 4f inches. Some variation is noticed in these 

 examples, but mostly in the smallest. Though it also has the colora- 

 tion with the six broad dark transverse bands distinct, these are 

 not very evident in the type. In all, the fourth to tenth dorsal 

 spines are more or less equal, and not regularly graduated from the 

 anterior to the last. 



This species is close to Mquidens rivulatus (Glinther), but differs 

 in several respects when examples of similar size are compared. 

 According to Regan, 7 M. rivulatus has the head 3 ; eye 3| to 4, inter- 

 orbital 3 to 3|, 7 or 8 rakers on lower part of gill-arch, dorsal spines 

 increasing in length to last, longest dorsal rays extend back to middle 

 or beyond in caudal length, caudal peduncle long or nearly long as 

 deep, a blackish vertical stripe below eye, 3 blue lines from eye to 

 maxillary, etc. 



(Azureus, blue; few, to bear; with reference to the pale bluish 

 in the coloration.) 



Faunal Works. 



Gunther, Albert. 1859. List of the Cold-blooded Vertebrata collected by 

 Mr. Fraser in the Andes of Western Ecuador. Proc. Zool. Soc. London, 

 1859, pp. 89-93. 



Second List of Cold-blooded Vertebrata collected by Mr. Fraser in the 



Andes of Western Ecuador. L. c, pp. (402-420) pisces 418-420. 



— — 1860. Third List of Cold-blooded Vertebrata collected by Mr. Fraser 



in Ecuador. L. c, 1860, pp. 233-240, PL 10. 

 Cope, E. D. 1870. Contribution to the Ichthyology of the Marafion. Proc. 



Amer. Philos. Soc, XI, 1870, pp. 559-570, with 9 cuts. 



1872. On the Fishes of the Ambyiacu River. Proc. Acad. Nat. Sci. Phila., 



1871 (1872), pp. 250-292, Pis. 3-16. 



Gill, T. 1870. On some New Species of Fishes obtained by Prof. Orton from 

 the Marafion or Upper Amazon and Napo Rivers. Proc. Acad. Nat. Set. 

 Phila., 1870, pp. 92-96. 



Steindachner, F. 1880. Zur Fisch-Fauna des Cauca und der Fliisse bei 

 Guayaquil. Denk. Ak. Wins. Wien., XLII, 1880, pp. 55-104, Pis. 1-9. 



Thominot, A. 1887. Sur un Saccodon d'espece nouvelle venant de l'Equateur. 

 Bull. Soc. Philomath., (7) VI, 1882, pp. 248-251. 



Boulenger, G. A. 1887. An Account of the Fishes collected by Mr. C. Buck- 

 ley in Eastern Ecuador. Proc. Zool. Soc. London, 1887, pp. 274-283, 

 Pis. 20-24. 



1 Acara rivulata Regan, Ann. Mag. Nat. Hist., (7) XV, 1905, p. 338 (type). 

 Rio Peripa, W. Ecuador. 



