46 The American Naturalist. [January, 



Fuess 9 has perfected an attachment for the microscope which enables 

 an observer to enclose with a diamond scratch any given spot in a thin 

 section, so that it may be easily identified for further study. 



Marsters 10 describes two camptonite dykes cutting white crystalline 

 limestones near Danbyborough, Vt. They differ from the typical 

 camptonite in being much more feldspathic than the latter rock. They 

 moreover, contain but one generation of hornblende, corresponding to 

 the second generation in the typical rock, and but few well developed 

 augite phenocrysts, although this mineral is found in two generations. 



A portion of Mte. S. Angelo in Lipari consists of a porous yellowish 

 pyroxeneandesite containing grains and partially fused crystals of cor- 

 dierite, red garnets and dark green spinel. 11 



Cole 12 declares that the " hullite " described by Hardman as an iso- 

 tropic mineral occurring in the glassy basalts of Co. Antrim, Ireland, 

 is in reality an altered portion of the rock's groundmass, and is no defi- 

 nite mineral substance. 



The same author 13 describes the old volcanoes of Tardree in Co. An- 

 trim as having produced rhyolitic lavas instead of trachytic ones as 

 has generally been stated. 



GEOLOGY AND PALEONTOLOGY. 



On the Species of Hoplophoneus.— Four species of Hop lop ho- 

 neus have already been described ; H. cerebralis Cope, H. oreodontis 

 Cope, H. primaevus Leidy and Owen, H. occidental™ Leidy. JKnotomius 

 atrox will be shown to be a synonym of the latter species. To these 

 may be added H. robustus and H. insolens herein described. The 

 following key may be valuable in determining the species from a few 



. Skull small, occiput nearly vertical. 



a. Superior sectorial with large anterior basal cusp. 



1- Pros. I H. cerebralis John Day. 



b. Superior sectorial with incipient anterior basal cusp. 

 'Neues Jahrb. f. Min., etc., 1895, I, p. 280. 



10 Amer. Geol., June, 1295, p. 368. 



11 Bergeat : Neues Jahrb. f. Min., etc., 1895, II, p. 148. 



12 Belfast Nat. Field Club Proceedings, 1894-5. 

 3 Geol. Magazine, No. 373, p. 303. 



