74 
ACTIN0PTERYG1I. 
single series ; minute styliform or conical teeth on some of the 
inner bones and tongue. Suboperculum and interoperculum ru 1 
mentary or absent ; brancbiostegal rays slender, about 10 to 40 
number, and no gular plate. Vertebral centra well ossified, an 
those of the abdominal region with robust transverse processes tor 
the support of the well-developed ribs ; a compound hypural bone 
at the base of the tail. Intermuscular bones present. Fin-fnl cra 
absent ; fin-rays more or less divided and articulated distallj 
dorsal and anal fins remote and more or less extended. Scali- 
thick and cycloidal, mosaic-like in structure, deeply imbricating- 
Ihe surviving members of this family are confined to the f 1 ' 0 ' 1 
waters of the tropics. Osteoglossum occurs in Tropical Ameri ca > 
Australia, and the East Indies 1 . Arapaima is characteristic 
Brazil and the Gnyanas ; while Heterolis is a Tropical African 
genus. 
The only extinct genus referable with certainty to the 
glossidse is Dapedoglossus, from the freshwater Eocene of ^ ° r . 
America. Brychcetus, from the marine London Clay of Shepp®} > 18 
also probably a member of the same family ; but its scales, so aX 
as known, do not exhibit the characteristic mosaic-like structure. 
Genus DAPEDOGLOSSUS, Cope. 
[Bull. U.S. Geol. Surv. Territ. vol. iii. 1877, p. 807-] 
99 
Syn. Phareodus, J. Leidy, Proc. Acad. Nat. Sci. Philad. 18/4, P- 
(undefined). 
Trunk much laterally compressed, comparatively short and c ®^’ 
and abdomen trenchant. Cleft of month extending to a P° 
below the middle of the orbit, the mandible not prominent, ^ 
marginal teeth long and slender, the inner teeth smaller, s oU _’ 
short and conical, apparently borne by the vomer, pal® a ’ 
tongue, and basihyals. Branchiostegal rays in uncertain num 
hut more than 10. Vertebra) about 45 in number, more caU 
than abdominal. Pectoral fins with thickened and excessi ■ ’ ^ 
elongated anterior ray ; pelvic fins small ; dorsal and anal 
directly opposed, the latter at least as much extended as 
former, and well-separated from the caudal fin, which is ve ^ 
slightly excavated at its hinder margin. Scales large, display - 
characteristic reticulate structure. 
Some points in the cranial osteology of Osteoglossum are describe 
T. W. Bridge, Proc. Zool. Soc. 1895, p. 302, pi. xxii.' 
