Additional Note on the Pteraspidian Fish. 323 



of the blood-pressure when stimulated, although very many 

 were tried. Some of the nerves that might be suspected as 

 depressors had a function (peripheral end) which is referred 

 to in the. preceding section. 



It may then be said that there is no nerve with the functions 

 of a physiological depressor in the Chelonians. 



(To be continued.) 



Additional Note on the Pteraspidian Fish 



found in New Brunswick. 



By G- F. Matthew, F.R.S.C. 



Since writing my former communication in reference to 

 the above organism, I have had opportunity for a further 

 examination, and add a few remarks herein to those pub- 

 lished in the October number of the Record. 



On comparison of the plates of this fish with those of the 

 Placoganoids of the Devonian Age, which alone of the' 

 earliest fishes are, at the present time, reputed to have been 

 armoured above and below, it [seemed probable that the 



C e 



hexagonal plate (c in the above figure) in the Acadian 

 fossil was the ventral plate, corresponding as it does in 

 form to the large ventral plate of Pterichthys ; and this 

 view seemed the more probable as this was the flatter, 

 and apparently the thinner of the two large plates of this 

 fish. 



A careful comparison with the known genera of Pteras- 



