36 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
species were left unnamed in both cases, except that provision was made for 
calling them both Megalopteri« securigera in the event of their being proved to 
represent but a single species of one and the same genus. The generic title 
Pelecyphorus is preocupied, 
Formation and Locality.— Devonian; River Ssjass, Government of St. 
Petersburg. 
Dinichthys pelmensis sp. nov. 
Plate 2, Fig. 4. 
The type of this species is represented by a specimen in the Schultze Col- 
lection belonging to the Museum of Comparative Zodlogy (Cat. No. 1375). 
It is from the Middle Devonian of Pelm, in the Eifel. 
The greater portion of the left side of the dorso-median is preserved entire, 
but on the right side there remains only an impression of the under surface of 
the bone. The carinal process is admirably preserved, and is of large size in 
proportion to the dorsal shield proper. It is deeply hollowed out posteriorly, 
and stands less nearly perpendicular to the surface of the shield than in the 
two preceding species. The height of the process is 1.2 cm., and its maximum 
breadth 0.5cm. The shield proper is 5.0 cm. long, and rather less than 4.5 cm. 
broad anteriorly. It is slightly arched transversely, and appears to have been 
emarginate in front. The sensory canals are distinctly traceable as far as the 
bone is preserved. That on the left side is seen to begin at a point about 
half way between the antero-posterior extremities of the shield, whence it con- 
tinues nearly parallel with the postero-lateral margin of the same, but stops 
short of the median line shortly in advance of the process. Only the bare 
termination of the canal belonging to the right side is preserved on the present 
specimen, The surface of the plate is covered with fine reticulating ridges, at 
the intersections of which traces of minute tubercles are discernib The 
effect of weathering, however, has been to reduce these, so that to the unaided 
eye the surface appears to be finely granulated, The thickness of the plate 
does not exeeed 2 mm. except in the vicinity of the median longitudinal ridge. 
Formation and Locality. — Middle Devonian ; Eifel District, 
Dinichthys eifeliensis Kayser. 
Plaie 3, Fig. 3; Plate 5, Fig. 4. 
1880. Dinichthys eifeliensis, E. Kayser, Zeitschr. deutsch. geol. Gesellsch., Vol. 
XXXII. p. 817. 
1895. Dinichthys eifeliensis, A. von Koenen, Ueber Fischreste des norddeutschen 
und böhmischen Devons (Abhandl. Ges. Wissensch. Göttingen, Vol. XL. 
pp. 16-18, Plate IV. Figs. 4, 5; Plate V. Fig. 1). 
The mandibles of this species are estimated by von Koenen to have meas- 
ured upwards of 50 em. in length, and as it is the only Dinichthyid previously 
known with certainty from this locality, we may safely refer to it the speci- 
