52 DK. J. W. EVANS ON A MONCHIQ,TJITE FEOM [Feb. I9OI, 



of the crystallization, in the manner already described, of the 

 analcime which now occupies them. The only alternative to this 

 explanation is to suppose that the spheres were originally formed by 

 the crystallization of leucite, and that this mineral and the leucite or 

 nepheline occupying the interspaces between the other minerals were 

 subsequently altered into analcime.^ It cannot be denied that this 

 is possible, but there is no evidence that such a change has taken 

 place ; and the absence in the spherical spaces of the concentrically 

 arranged inclusions so characteristic of leucite is a serious difficulty 

 in the way of such an hypothesis. 



VII. Bibliography. 

 I. Analcime and Monchiquites. 



[1] Glockee, E. F. ' Ueber einige Ersclieinungen an Kalkspathformen ' Nov. 



Act. Acad. Caes. vol. xxiii, pars ii, pp. 809-11 (1852). 

 [2] TscHERMAK. ' Uebei" secundare Mineralbildungen in dem Griinsteingebirge 



bei Neutitschein ' Sitzuugsber. kais. Akad. Wissensch. Wien, vol. xl, 



pp. 122-23 (1860). 



[3] ♦ ' Felsarten von ungewohnlicher Zusammensetzuiig in den Umgebungen 



^Von Teschen & Neutitschein ' Ihid. vol. liii,pp. 275-81 (1866). 

 [4] Boric KT, E. ' Petrographische Studien an den Phonolithgesteinen Bohmens ' 



Archiv der Naturwiss. Landesdurchforsch. Bobm. vol. iii, sect, ii, pp. 66-74 



(1873). 

 [5] . ' Petrographische Studien an den Basaltgesteinen Bohmens ' Ibid. 



vol. ii, sect, ii, pt. ii, pp. 172-82 (1874). 

 [6] MoHL, H. ' Mikromineralogische Mittheilungen ' Neues Jahrb. pp. 696-98 



(1875). 

 [7] Werveke, L. van. 'Ueber den Nephelin-Syenit der Serra de Monchique im 



siidlichen Portugal & die denselben durchsetzenden Gesteine ' Ihid. vol. ii, 



pp. 177-86 (1880). 

 [8] RoHRBACH, Carl E. M. ' Ueber die Eruptivgesteine im Gebiete der schlesisch- 



mahrischen Kreideformation ' Tscherm. Min. Petr. Mitth. vol. vii, pp. 31-33 



(1886). 

 [9] LiNDGREN, W. ' Eruptive Rocks from Montana ' Proc. Calif. Acad. Sci. 



ser. 2, vol. iii, pp. 51-57 (1890). 

 [10] Hunter, M., & H. Rosenbusch. ' Ueber Monchiquit, ein camptonitisches 



Ganggestein aus der Gefolgschaft der Elaolithsj^enite ' Tscherm. Min. Petr. 



Mitth. vol. xi, p. 445 (1890). 

 [11] Williams, J. R. 'The Igneous Rocks of Arkansas ' (with Additions by J. F. 



Kemp) Ann. Rep. Geol. Surv. Arkans. vol. ii, pp. 66, 78-80, 107-16, 290- 



95,352-54,393-402(1890). 

 [12] Rosenbusch, H. ' Mikroskopische Physiographie der petrographisch-wichtigen 



Mineralien ' 3rd ed. pp. 331-34 (1892). 

 [13] Kemp, J. F., & V. F. Marsters. 'The Trap-Dykes of the Lake Champlain 



Region ' U.S. Geol. Surv. Bull. No. 107, pp. 32-39 (1893). 

 ri4] ZiRKEL, F. ' Lehrbuch der Petrographie ' 2nd ed. vol. ii, p. 680 (1894). 

 [15] HiBSCH, J. E. 'Beitrage zur Geologie des bohmischen Mittelgebirges ' 



Tscherm. Min. Petr. Mitth. vol. xiv, pp. 99-100 (1895). 

 [16] Fairbanks, H. W. ' On Analcite-Diabase from San Luis Obispo County^ 



California' Bull. Dep. Geol. Univ. Calif, vol. i, pp. 273-300 & pis. xv-xvi 



(1895). 



ri7] . ' The Geology of Point Sal ' Ihid. vol. ii, pp. 19-38 & pi. ii (1896). 



[18] Weed, W. H., & L. V. Pirsson. 'Geology of the Castle Mountain Mining 



District (Montana) ' U.S. Geol. Surv. Bull. No. 139, pp. 114-17 & 136 (1896). 

 [19] Pirsson, L. V. 'On the Monchiquites or Analcite-Group of Igneous Rocks' 



Journ. Geol. Chic. vol. iv, p. 679 (1896). 



^ This is supposed to have been the case with the ' leucite-monchiqiiites' of 

 Bohemia, where there are now similar spaces filled with analcime [1(5] p. 100, 

 [20] p. 545, & [24] p. 234. I can see no evidence of such a change in a micro- 

 scope-section of a specimen from Babutin, which I owe to the kindness of 

 Prof. Judd. The rock has, however, suffered considerable alteration, which is 

 not the case with the Girnar monchiquite. , 



