EIGENMANN: THE PYGIDIID/E, A FAMILY OF SOUTH AMERICAN CATFISHES. 353 



In the specimens collected by Haseman the color-marking is less regular, the 

 sides and back with unsymmetrically placed spots, largest on the caudal peduncle, 

 smallest on top of the head, sometimes arranged in a series along the middle of the 

 sides; the spot at the base of the caudal largely above the middle. 



Genus X. Stegophilus 36 Reinhardt. (Plate XXXVII.) 

 Stegophilus Reinhardt, Vidensk. Meddel. Naturh. Foren., Kjobenhavn., 1858 



(1859), p. 79, pi. II. 



Type. — Stegophilus insidiosus Reinhardt. 



No nasal or mental barbel, lower barbel at angle of mouth excessively minute, 

 a minute dermal flap below the lower barbel; mouth very wide, inferior; eye large, 

 superior; posterior nares between the front parts of the eyes; opercle and inter- 

 opercle with several spines; gill-opening narrow, about a third as wide as the mouth, 

 in front of the pectoral, the membrane not forming a free margin; first pectoral ray 

 not produced in a filament; origin of ventral one and a half to two times as far from 

 snout as from caudal; caudal rounded, not greatly contracted at base, the accessory 

 rays not conspicuous; origin of dorsal behind the vertical from the origin of the 

 ventrals; teeth very numerous, in regular series, those in the middle of the upper 

 jaw larger than the others. 



1. Stegophilus insidiosus Reinhardt. 

 Stegophilus insidiosus Reinhardt, I. c, p. 79-97; Gunther, Cat. Fishes Brit. Mus., 



V, 1864, p. 276; Lutken, Velhas Flodens Fiske, p. 15; Vidensk. Selsk. Skr. 



(5), Afd. XII, 1875, p. 135, and I, text figures 1-3 (Rio das Velhas) ; Eigenmann 



& Eigenmann, Proc. Cal. Acad. Sci. (2), II, 1889, p. 55; Occasional Papers 



Cal. Acad. Sci., I, 1890, p. 344; Proc. U. S. Nat. Mus., XIV, 1891, p. 37; 



Eigenmann, Reports Princeton Univ. Exped. Patagonia, III, 1910, p. 400. 



Habitat. — Parasitic in large fishes (Pseudoplatystoma orbignianum = coruscans) 

 of the San Francisco basin and free on sand bars of the upper San Francisco basin. 

 7551, C. M., one, 32 mm. Opposite Januaria. Dec. 12, 1907. Haseman. 



This example is the first one secured since Reinhardt obtained his specimens 

 from the gill-chamber of a large catfish, Pseudoplatystoma. Haseman took his 

 specimen on Dec. 12, 1907, from the sandy shore of an island in the Rio San Fran- 

 cisco, in front of the town of Januaria. If this specimen is really identical with 

 those secured by Reinhardt from the same river basin, Stegophilus appears to have 

 the general habit of members of the family of burrowing in sand as well as the pecu- 

 liar habit of entering the gill-chambers of other fishes. This double, Jekyl and 



36 arkyos, to = a roof ; ^iXos, o = a lover, i. c, loving a covered home, in allusion to its habit of living 

 in the gill-cavities of other fishes. 



