BUFFALO SOCIETY OF NATURAL SCIENCES 27 



E 2374 The spetimen is contained in a piece of shale, 15 by 21 cm., 

 which had broken out of its place and was picked up at 

 the foot of the bank. It must have been weathered out 

 by ice or frost. The specimen represents a large indi- 

 vidual, larger than the one figured by Hussakof , and dis- 

 plays the following plates: 



Left Suborbital (SO) . — This plate is shown in inner view. 

 The anterior process is well developed; its superior sur- 

 face is broad and excavated for lodging the eye. The 

 whole plate closely resembles that of Dinichthys. The 

 upper margin is somewhat broken, but judging from one 

 point at which the entire width of the element is pre- 

 served, it would seem that the blade (or plate minus the 

 process), was deeper, i.e., broader, than in other species 

 of Coccosteus. 



Length, including process, 81 mm.; max. depth 

 (measured at hinder fourth of plate), about 40. 



Left Mandible (Mnd). — This is represented by the im- 

 pression of the outer face of a mandible lacking the front 

 half of the functional portion and the posterior extremity of 

 the blade portion. The depth of the blade at its middle 

 is 25 mm. The mandible was therefore of considerable 

 size for a Coccosteus; but this is in keeping with the large 

 size of the specimen as a whole. The functional margin 

 of the mandible was a continuous bevelled edge, with 

 denticles (three in number) only at the posterior extrem- 

 ity where it descends to join the blade portion. It was 

 thus strikingly like that of Dinichthys. To anticipate 

 the criticism that the specimen is in fact a Dinichthys and 

 not a Coccosteus, we may say that we have observed a 

 similar condition in Coccosteus mandibles belonging to 

 old individuals; one in the British Museum, which is free 

 of all matrix, and which unquestionably is Coccosteus 

 coming from the Old Red Sandstone, also shows a 

 bevelled, non-denticled cutting margin; the "teeth" 

 apparently wore off with age, persisting only at the pos- 

 terior angle where they are not so much exposed to wear. 



Left Antero-superognathal {A SO). — This element is 

 shown in inner view, and exhibits the area against which 

 the mandibular beak closed. This area is striated by 



