XVIII CROSSOPTERYGII 479 
Bay, Canada; Gyroptychius, Old Red Sandstone, Scotland ; 
Rhizodopsis! (Fig. 274), Carboniferous of England, Scotland, 
Silesia, and North America; Strepsodus, Carboniferous of Great 
Britain, Ireland, and North America. 
a S 
Frc. 275.—Restoration of T'ristichopterus alatus. Old Red Sandstone. c/, Clavicle. 
Remaining reference letters as in Fig. 274. (After Traquair.) 
= 
Fic. 276.—Restoration of Lusthenopteron foordi. Upper Devonian of Scaumenac Bay, 
Canada. The scales have been omitted in the hinder part of the body to show the 
vertebral column and the radials of the median fins. c¢/, Clavicle; @.c/, infra- 
clavicle ; s.cl, supra-clavicle ; for other reference letters see Fig. 274. x about 3. 
(After Whiteaves. ) 
Fam. 3. Holoptychidae (Dendrodontidae)—Scales cycloid. 
Pectoral fins acutely lobate ; pelvic fins short and somewhat 
obtusely lobate. Tail heterocercal. Teeth similar to those of 
- 
Fic. 277.—Restoration of Holoptychius femingt. x24. (From Traquair.) 
the Rhizodontidae but more specialised, the enamelled dentine 
infoldings being much more complicated, presenting a radiating 
! Traquair, Zrans. Roy. Soc. Edinb. xxx. 1881, p. 169. 
