276 .MEMOIRS OF THE CARNEGIE MUSEUM. 



< Trichomycteridce Regan, Ann. & Mag. Nat. Hist. (8), VIII, 1911, p. 57. 

 = Trichomycteridce Ribeiro, Archivos do Museu National, XVI, 1912, p. 219. 



Limits of the family Pygidiidce. (Plates XL and XLI.) 



Giinther, in his "Catalogue of the Fishes of the British Museum," V, 1864, pp. 

 271-277 ', arranges the then known members of the Pygidiidce under three "Groups," 

 belonging to two of his eight Subfamilies of the Siluridce. His seventh Subfamily, 

 the Siluridce Opisthopterce, consists of his Fifteenth Group, the Nematogenyina 

 (Heptapterus and Nematogenys) and the Sixteenth Group, the Trichomycterina 

 ( Trichomycterus ( = Pygidium), Eremophilus, Bariodon). His Eighth Subfamily, the 

 Siluridce Branchicolce, consists of his Seventeenth Group, the Stegophilina (Stego- 

 I ih Has and Vandellia). 



The genus Heptapterus 11 included in his Fifteenth Group, was shown by us in 

 the American Naturalist, July, 1888, p. 648, to "have no real affinity with the 

 Pygidiidce." 



We do not now feel justified in joining the Cetopsince to the family. 



The Pygidiidce, as here understood, are the Pygidiince (exclusive of Pariolius 

 and the Stegophilince of the family, as described by Eigcnmann & Eigenmann, in 

 the American Naturalist, July, 1888, and Occasional Papers of the California 

 Academy of Sciences, I, 1890. The species known at the time, thirty-six in number, 

 belonging to eight genera, were reviewed in t he last named paper. The Cetopsince, 

 included in the papers mentioned, constitute a distinct family. Regan (Ann. &■ 

 Mag. Nat. Hist. (8), VIII, 1911, p. 574) has united the Pygidiince and Stegophilince 

 in his Trichomycterince of his Trichomycteridce = Pygidiidce. The family includes 

 the South American Nematognaths without an adipose fin, with the dorsal over or 

 behind the ventrals; posterior air-bladder obsolete; the anterior minute, in two 

 lateral parts, enclosed in bony capsules with a complete osseous floor, united to the 

 exoccipital and epiotic bones proximally and to the suprascapula distally; neural 

 spine of the coalesced vertebrae very low, not as high as that of the vertebras fol- 

 lowing them; parapophysis of the vertebrae following the capsule short; skull de- 

 pressed, entirely closed in front, without an open space between the osseous roof of 

 the mouth and the ethmoid; vomer and palatines weak, without teeth; clavicles 

 wide, scoop-shaped, meeting below. The place of the adipose fin sometimes occupied 

 in part by numerous accessory caudal rays; none of the fin-rays modified into 

 spines; narcs remote from each other, the anterior one frequently provided with 

 a barbel; the maxillary ending in a short barbel; the lower lip usually ending in 



11 Related to //< ptapterus is (he genus Phreatobius, for an account of which see the Appendix to this 

 paper. 



