196 FISHES OF WESTERN SOUTH AMERICA 
Genus 83: XENOCARA Regan 
Chaetostoma (in part) Heckel (Tschudi), 1846, Fauna Peru., 25. 
Xenocara Regan, 1904, Trans. Zool. Soc. London, XVII, 251; 
Kigenmann, 1905, Science, n.s. XXI, 794; 
Kigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 410; 
Eigenmann, 1912, Mem. Carnegie Mus., V, 235. 
Type: Chaetostoma latifrons Giinther 
Rivers of much of South America 
Interopercle movable, usually spinous; mouth narrow, mandible much less in 
width than interorbital; teeth of respective Jaws subequal; snout with naked margin; 
skull characterized by stays separating superficial bones from the brain case, the 
outer shell consisting of portions of the frontals, postfrontals, supraoccipitals, and 
squamosals. 
193. NENOCARA LATIFRONS (Ginther) 
Chaetostomus latifrons Giinther, 1869, Proc. Zool. Soc. London, 426; 
Eigenmann and Eigenmann, 1889, Proce. Cal. Acad. Sci., (2), I, 46; 
Kigenmann and Higenmann, 1890, Occ. Papers Cal. Acad. Sei., I, 442. 
Xenocara latifrons Regan, 1904, Trans. Zool. Soc. London, XVII, 253, pl. xv, fig. 1; 
Kigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 410. 
Peruvian Amazon 
Represented by the type, 160 mm., in the British Museum. 
Genus 84: ANCISTRUS Kner 
Ancistrus Kner, 1853, Denksch. Kix. Akad. Wiss. Wien, VII, 272, sp.; 
Bleeker, 1863, Nederl. Tijdsch. Dierk., I, 77, czrrhosus; 
Eigenmann and EKigenmann, 1890, Occ. Papers Cal. Acad. Sei., I, 444; 
Regan, 1904, Trans. Zool. Soc. London, XVII, 221; 
Kigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 411. 
Xenocara (in part) Regan, 1904, Trans. Zool. Soc. London, XVII, 251. 
Type: Hypostomus cirrhosus Cuvier and Valenciennes 
Panama to the Guianas and La Plata basin 
Plecostominae having snout granular to margin (sometimes naked in females), 
tentaculate, the tentacles more numerous in the males; the interopercle a movable 
plate, spinous or bristly; teeth of premaxillaries and dentaries subequal and in 
about the same number. 
194. ANCISTRUS HOPLOGENYS (Ginther) 
Chaetostomus hoplogenys Giinther, 1864, Cat. Fish. Brit. Mus., V, 247. 
Ancistrus hoplogenys Eigenmann and Eigenmann, 1889, Proc. Cal. Acad. Sci., (2), IH, 48; 
Eigenmann and Eigenmann, 1890, Occ. Papers Cal. Acad. Sci., I, 448; 
Eigenmann and Eigenmann, 1891, Proc. U.S. Nat. Mus., XIV, 43; 
