W. W. Watts— Per lit ic Structure. 15 



Gcrahlattina clathrata (Heer), Manebach, Saxe Weimar. 



,, Geinitzi (Gold.), Lobejiin, Saxony. 



,, Germari (Gieb.), Wettin, Saxony. 



„ Goldcnbergi (Malvr), Manebach, Saxe "Weimar. 



,, Mahri (Gold.), Manebach, Saxe Weimar. 



,, Mihisteri, Scndd., Wettin, Saxony. 



,, producta, Scudd., Wettin, Saxony. 



,, robusta, Kliv., Wemmetsweiler, Rhenish Prussia. 



,, Rollei (Deichm.), 1 Griigelbom, Ehenish Prussia. 



,, scaberata (Gold.), Altenwald, Rhenish Prussia. 



,, Weissiana (Gold.), Briicken, Rhenish Bavaria. 



Anthracoblattina camerata, Kliv., Dudweiler, Rhenish Prussia. 



,, Dresdensis (Gein. -Deichm.), Klein Opitz, Saxony. 



,, ineerta, Kliv., Dudweiler, Rhenish Prussia. 



,, Lubnensis (Kusta), 2 Lubna, Bohemia. 



,, porrecta (Gein.), Weissig, Saxony. 



,, Remigii (Dohrn), Cusel, Rhenish Bavaria. 



,, Ruckerti (Gold.), Stockheim, Bavaria. 



,, Scuddcri, Gold., Wemmetsweiler, Rhenish Prussia. 



,, sopita, Scudd., Weissig, Saxony. 



,, speetabilis (Gold.), Weissig? and Lobejiin, Saxony. 



,, Wagneri, Kliv., Lobejiin, Saxony. 



,, Winteriana (Gold.), Dudweiler, Rhenish Prussia. 

 Bermatoblattiiia Kirkbgi (Woodw.), Fifeshire, Scotland. 



,, Labachensis (Gold.), Labach, Rhenish Prussia. 



,, Wemmetsweileriensis (Gold.), Wemmetsweiler, Rhenish Prussia. 

 Progonoblattina Fritschii (Heer), Manebach, Saxe Weimar. 



,, Helvetica (Heer), Erbignon, Switzerland. 

 Oryetoblattina Arndti, Kusta, Tfemosna, Bohemia. 



,, oblong a, Deichm., Weissig, Saxony. 



,, reticulata (Germ.), Wettin, Saxony. 

 Petrablattina gracilis (Gold.), Labach, Rhenish Prussia. 

 Leptoblattina exilis, Woodw., Dudley, England. 



,, insignis (Gold.), Dudweiler, Rhenish Prussia. 



III. — On Perlitic Structure. 

 By W. W. Watts, M.A., F.G.S. 



I HAVE received from my friend Mr. W. F. Smeeth a paper 

 entitled " A Perlitic Pitchstone from the Tweed River, New 

 South Wales, with remarks on the so-called Perlitic Structure in 

 Quartz," published by the Eoyal Society of New South Wales. 

 While thanking him for his courtesy in making me acquainted with 

 his views, I desire at the same time to express my sense of the 

 kindly way in which he has criticized, though often adversely, 

 certain statements already published by me. 3 It may be of interest 

 to give to the readers of the Geological Magazine an abstract of 

 the excellent piece of work which Mr. Smeeth has done, as well as 

 to draw attention to the points in which he has compelled me to 

 agree with him and to remark on those on which there is still some 

 difference of opinion between us. 



The glassy matrix of the rock, which is admirably perlitic, con- 

 tains phenocrysts of quartz, sanidine, albite, and hypersthene. The 

 last mineral is in small distinct grains of prismatic habit, which 



1 Etoblattina Rollei, Deichm. 



2 Blatl'iiHi (Anthracoblattina) Lubnensis, Kusta. 



3 Quart. Journ. Geol. Soc. vol. l (1694), pp. 367-76. 



