BUFFALO SOCIETY OF NATURAL SCIENCES 69 



A detailed description of the plate accompanied by a pen-and-ink 

 figure was published by Ringueberg in 1884.^^ The plate was cor- 

 rectly identified as a dorsomedian, but was figured upside down — 

 an error excusable at that time when so little was known concern- 

 ing Dinichthys and so few figures were available. 



The plate is well represented in Plate 15, figure 2. It is of small size, 

 II cm. in length in the middle line (without the process), and 14 cm. 

 in greatest width. Its most distinctive character is the emargination 

 of the front halves of the lateral margins. In this, however, it is not 

 imique, for a dorsomedian of much larger size, from the Cleveland 

 shale, in the American Museum collection, shows the same form. This 

 feature distinguishes these two plates at a glance from dinichthyid 

 dorsomedians. It is possible that the plate belongs to the species we 

 have named Stenognathus niixeri (page 75); it is of about a size to 

 go with the type of the latter. However, ventral plates of the latter 

 show a fine tuberculation which is not evident in ,5. ringuehergi. The 

 fact that a similar shaped plate occurs in the Cleveland shale is inter- 

 esting in view of the occurrence of Stenognathus m that formation also. 



The plate is embedded in matrix and displays the dorsal, or upper 

 surface. The extremity of the keel, forming the usual dinichthyid 

 "knob" process, is well shown. 



Horizon and locality. — Portage shale (Rhinestreet) : Sturgeon 

 Point, shore of Lake Erie, N. Y. Collected by Mr. E. N. S. Ringue- 

 berg and preserved in his private collection at Lockport, N. Y. 



Besides the type just described, we have in hand a remarkable 

 specimen of this species collected by Mr. Bryant in the summer of 

 1916. The specimen is of great interest for the fact that it shows a 

 part of the notochord, with neural and haemal arches. It is the 

 second specimen of a Stenognathus found with the notochordal region 

 preserved. Although no dental elements are preserved in the speci- 

 men, still we regard it as belonging to the genus Stenognathus, for the 

 reasons that the form of the dorsomedian — especially as shown in the 

 type — excludes it from the genus Dinichthys; but the thinness of the 

 ventral plate, coupled with the fact of its size and resemblance to its 

 homolog in S. gouldi, would indicate that the specimen belongs in 

 Stenognathus. 



E 2595 The specimen (PI. 69, fig. i), consists of a slab of shale, 65 by 

 37 cm., displaying the dorsomedian (DM), a postero- 



2' Ringueberg, E. N. S.: A new Dinichthys from the Portage Group of Western New York. Amer. 

 Journ. Sci., 3 ser., xxvii 476-478, 2 figs. 



