36 BULLETIN : MUSEUM OF COMPAEATIVE ZOOLOGY. 



species were left unnamed in both cases, except that provision was made for 

 calling them both Mer/alopterix 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 Zoology (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 0.5 cm. 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 discernible. 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 exceed 2 ram. except in the vicinity of the median longitudinal ridge. 



Formation and Locality. — Middle Devonian ; Eifel District. 



Dinichthys eifeliensis Katser. 



Plate 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 Fisclireste des norddeutschen 



und bohmischen Devons (Abhandl. Ges. Wissensch. Gottingen, 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 cm. in length, and as ft is the only Dinichthyid previously 

 known with certainty from this locality, we may safely refer to it the speci- 



