514 GEOLOGY AND MINERALOGY. 



the most varied kind, winding up with, " a bead protector against 



heat, coup de soleil, &c." 



It is not necessary that we should commend the Canadian Almanac 



to our readers, but we may say of it that in this twelfth appearance 



there is no diminution of the care, industry, and experience, which 



have secured for it its good credit in former years. 



D.W. 



SCIENTIFIC AND LITERARY NOTES. 



GEOLOGY AND MINERALOGY. 



TEINUCLEUS CONCENTRICUS. 



(T. Caractaci, Murch. ; T. Goldfussi, Barr.) 



The accompanying figure represents the glabella (enlarged) of an example of 

 Triiwcleus concentricus, obtained from the Trenton Limestone,ia the 

 neighbourliood of the Montmorenci Falls, near Quebec. It is depriv- 

 ed of its crust. In the elevated centre, two prominent tubercles 

 occur, one a little in advance of the other in the direction of the axis. 

 From the foremost of these run two series of very minute tubercles 

 towards the anterior margin of the glabella, followed, on the outside, """-Ssi^ 

 by a faintly-raised line. The latter, as shown in the figure, is con- 

 tinuous along the front edge of the glabella. Finally, at the contracted base of 

 the glabella, two large tubercles are situated — one on each side, with a semi- 

 circular depression just in front of them. 



In the figures of this species given by Professor Hall in his Palaeontology of the 

 State of New- York, there are no indications of the peculiar tubercles occurring on 

 the glabella of the present specimen ; nor are they noticed by Sir Roderick Mur- 

 chison, in his original figures and description of T. Caiaetaci (= T. Goneentricus) 

 in the " Silurian system." They occur, however, more or less distinctly, on all the 

 Canadian specimens that have come under our observation. Barrande, in his great 

 work on the Silurian Basin of Bohemia, describes the basal tubercles and depres- 

 sions (mentioned above) in his Trinwleus Goldfussi, a species evidently identical 

 with T. Concentricus. Barrande figures also the two central tubercles as occurring* 

 according to his observations, in certain examples of T. Goldfussi ; but he does not 

 appear to have remarked the series of smaller tubercles as shewn in our figure- 

 He looks upon the central tubercles as mere ornaments, disappearing with age, and 

 hence of no importance as specific characters. As, however, the supposed "eye- 

 tubercles" present on the cheeks of some species of Trinucleus, also appear to be 

 obliterated hy age, we cannot look upon these glabella-tubercles as wholly unim- 



