Section IV, 1888. [ 49 ] Trans. Roy. Soc. Canada. 



IV. — On soDie Remarkable Organisms of the Silurian and Devonian rocks in Southern 

 New Brunswick. By G. P. Matthew, M.A. 



(Read May 31, 1888.) 



lu the coixrse of the last two years several peculiar organisms have been found in the 

 neighborhood of St. John by the author and by a member of the Natural History Society 

 of New Brunswick, Mr. W. J. Wilson, which latter have been placed in the writer's hands 

 for description. The following paper has been prepared to give expression to the remark- 

 able features of these newly-discovered species. 



A. — Organisms of the Silurian System. 



DiPLASPis AcADiCA (Plate IV, figs. 1-4). 



Pternspis Amdica, Canadian Record of Science, Vol. II, p. 251. 



Diplaspis Acadica, Bulletin of Natural History Society of New Brunswick, No. VI, p. 69. 



In a short communication to the Canadian Record of Science (Vol. II, p. 251), the writer 

 drew attention to the occurrence of jjeculiar fish plates in the Silurian,^ rocks of the 

 Nerepis Hills in Southern New Briinswick, referring them to the genus Pteraspis. Sub- 

 sequently, on further examination and comparison, it was seen that these plates could not 

 be those of a species of Pteraspis, though they belong to the family of which this genus 

 forms a part. Nor could they be referred to any known genus of Pteraspidian fishes, 

 owing to the fact that they formed the covering of a fish that was armoured below as well 

 as above, a feature not recognized in any genus of the family hitherto described.' 



As this fish — -one of the oldest vertebrate animals known — presents points of struc- 

 ture of peculiar interest, I have in the following paper described its characteristics more 

 at length than in previous papers, and given figures representing the form, arrangement 

 and ornamentation of the plates. In this paper are also given descriptions of the several 

 organisms found in the shales in which this fish occurs. 



'&■■ 



I. — Description of the Species. 



Hitherto all the fishes of this family have been spoken of as having plates on the 

 head, back and sides only, but the one I am about to describe had a ventral plate as well, 



' The <erm Silurian is used in this paper to distinguish the strata from ihe Llandovery to the Upper Ludlow, 

 both inclusive. 



^ Since writing the above I have received from Dr. F. Schmidt, of St. Petersburg, Russia, a pamphlet describing 

 a filurian pteraspidian fish found in Silesia, in which pamphlet he speaks of a ventral plate, and refers certain fish 

 plates described by Prof. Lankester as Scaphaspis to the position of ventral plates of pteraspidian fishes. From 

 this it will be seen that Dr. Schmidt has taken the same view of the armour of the pteraspids as has been suggested 

 by the author in this paper. 



Sec. IV, 1888. 7. 



