292 John Parkinson — Gabhro of Pegli, JSf. Italy. 



Tt has not so well developed a cingulnm as have typical molars 

 of 31. tapiroides (turicensis), and the ridges are not so high in 

 proportion to the other dimensions of the tooth. In place of the 

 oblique fold of enamel traversing the face of each ridge which is 

 seen in typical (but not in all) specimens of molars referred to 

 M. tapiroides,^ we have here a breaking up of the ti'ansvei'se ridge 

 itself into semi-detached columns. On the whole it comes nearest 

 amongst described molars to those called M. Pyrenaicus by 

 Falconer. This If. Pyrenaicus is essentially a Mastodon angustidens 

 which is not angustident, and that perhaps is the best description 

 which can be given of the present tooth. I should be inclined, 

 supposing that the species ' M. Pyrenaicus, Falo.,' is to be considered 

 as a synonym of M. angiistidens, Cuv., to recognize such broad 

 molars of the M. angustidens type as belonging to Mastodon 

 angustidens, Cuv., var. latidens. 



In any case we have to go to the Middle Miocene for the species 

 with which to associate this Suffolk Mastodon, and this fact is well 

 in harmony with the age indicated by the once adhering matrix, 

 viz., one anterior to that of the Diestien or Black Crag of Antwerp. 



EXPLANATION OF PLATE XI. 



Fig. 1, view of the tipper surface, and Fig. 2, side view of the trilophodont 

 upper penultimate molar of 3Iastoclo]i angustidens, var. latidens, from the hase of 

 the Red Crag of Suffolk, preserved in the Yorkshire Philosophical Society's Museum, 

 York. Originally figured with its valleys still filled by the peculiar Diestien matrix, 

 Avhich has since been removed. (See Quart. Journ. Geol. Soc, 1870, vol. xxvi, 

 p. 507, pi. xx.\iv, figs. 1 and 2.) Drawn of the natural size. 



II. — The Glaucophane Gabbro of Pegli, North Italy. 

 By John Parkinson, F.G.S. 

 (PLATE XII.) 



IN a paper published some years back on the Tuscan and Ligurian 

 Serpentines^ Professor Bonney has noticed incideatally the occur- 

 rence of glaucophane in the gabbro associated with these rocks at 

 Pegli, a village to the west of Genoa; and later added a rather 

 fuller description towards the end of his paper^ on " The Glaucophane 

 Eclogite of the Val d'Aoste." Last year I spent a few days at Pegli 

 for the purpose of examining the rocks at the village and in its 

 neighbourhood, when I found the gabbro in some abundance, in 

 consequence, as I think, of blasting for road-making. The specimens 

 then collected have disclosed on examination a few points of interest 

 which may not, I hope, be deemed a superfluous addition to the 

 accounts already published. Those have been rather numerous. 

 Dr. G. H. Williams has briefly described* a glaucophane containing 

 rock from this neighbourhood, which he calls an amphibolite, 

 and, later, Sfcefani ^ has called in question the propriety of the term 



1 Fragments of molars showing this typical fold have been recorded by me from 

 Suffolk: Quart. Journ. Geol. Soc, 1870. 



2 Gbol. Mag., Dec. II, Vol. VI (1879), p. 363. 



3 Min. Mag., vol. vii (1885-7), p. 5. 



* Neues Jahrb. fiir Min. Geol., 1882, Bd. ii, p. 201. 

 » Boll. d. Soc. Geoi. ItaL, vol. vi (1887), p. 233. 



