382 FISHES OF WESTERN SOUTH AMERICA 
The Guianas to Peruvian Amazon; Rio Paraguay 
15811, 1, 220 mm., Rio Morona, Allen, October, 1920. 
15815, 1, 161 mm., Rio Pacaya, Allen, August, 1920. 
A marine relict reaching the extreme western margin of the Amazonian flood 
plain and the fringes of the Andean highlands. 
Genus 197: TYLOSURUS Cocco 
Tylosurus Coceo, 1833, Giorn. Sci. Lett. Sicilia, XLII, no. 124; 
Bigenmann and EHigenmann, 1891, Proc. U. 8. Nat. Mus., XIV, 65; 
Jordan and Gilbert, 1882, Bull. U. S. Nat. Mus., XVI, 372; 
Higenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, IIT, 462. 
Type: Tylosurus cantraini Coeco = T. acus Lacépéde and Hsox imperialis 
Rafinesque 
Both coasts of the Americas; West Indies; rivers 
Greatly elongate, subcylindrical; both jaws extended into a beak, the lower 
somewhat the longer; teeth of both jaws in bands, one band of small, sharp teeth, 
another of larger, unequal, conical ones; maxillaries and premaxillaries united; 
scales small, deciduous; lateral line along the belly, median on the tail; separated 
from Belone by lack of gill-rakers and vomerine teeth. 
491. TyLOSURUS AMAZONICUS (Steindachner) 
Belone amazonicus Steindachner, 1875, Sitzb. Ik. Akad. Wiss. Wien, LX XII, 66. 
Tylosurus amazonicus Kigenmann and Higenmann, 1891, Proc. U.S. Nat. Mus., XTV, 65; 
Jordan and Evermann, 1896, Bull. U.S. Nat. Mus., XLVIT, 1, 712; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, ITT, 462. 
Para to Peru 
15812, 2, 180 and 212 mm., Rio Paranapura, Yurimaguas, Allen, November, 1920. 
15813, 2, 95 and 110 mm., Gosulimacocha, Allen, October, 1920. 
16161, 2, 40 and 52 mm., Rio Pichis, Pto. Bermudez, Allen, July, 1920. 
None of the familiars of the frontier post at Puerto Bermudez, so far as could 
be ascertained, had ever seen a specimen until they were shown my collections. 
At this point they are separated by more than three thousand miles of fresh water 
from their salt-water kindred. 
Order ACANTHOPTERI 
Family XX: Nandidae 
Genus 198: MONOCIRRHUS Heckel 
Monocirrhus Heckel, 1840, Ann. Wien. Mus., IT, 439; 
Gunther, 1861, Cat. Fish. Brit. Mus., III, 371; 
Eigenmann and Eigenmann, 1891, Proc. U. 8. Nat. Mus., XIV, 66; 
Kigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 466. 
