1866.] 



YOUNG CAllBONIFEROFS GLYPTODir TERINES. 



597 



lated by similar anastomosing ridges. The pectoral arch is well 

 developed, and supports a subacutely lobate fin with rounded margin. 

 The two dorsals, the ventrals, and anal are of nearly equal size, and 

 opposite each other respectively. The tail is heterocereal and 

 rhomboidal. 



Figs. 1-8. — Illustrating the teeth and scales of some new genera of 

 Carhoniferous Fishes. 



Fig. 1. Rhomboptychius, tooth. 



2. Rhomboptychius, scale. 



3. Strepsodus, tooth. 



4. E.hizodus, scale. 



Fig. 6. Rhizodus, tooth. 



6. Megalichthys, scale. 



7. Dendroptychius, scale. 



8. Rhizodopsis, scale. 



The scales vary somewhat in size and shape on different parts of 

 the body ; they are arranged in very oblique series, and range from 

 nearly orbicular to elongate cordate. The upper surface is orna- 

 mented with concentric and radiating striae; the latter are most 

 strongly marked over two triangular areas whose bases correspond 

 to the centre of the anterior and posterior margins respectively ; the 

 former occupy the lateral surfaces between those areas. The under 

 surface is marked by more or less numerous growth-lines, presents 

 a subcentral raised boss, and is usually pitted over a small area 

 immediately behind the centre ; no corresponding tubercles are visible 

 on the upper surface, whose free area averages two-thirds of the 

 whole surface. The lateral line is well marked and nearly straight. 



The notochord is persistent ; the osseous rings surrounding it are 

 short and narrow. The upper arches are distinct and well ossified. 



These characters are in the main those of the family to the cycloidal 

 section of which Holo^tychius belongs. But from that genus Rhi- 



