Vol. 57.] MOUKT &IKNAR, JTJNAGARH. 53 



[20] RosENBUSCH, H. ' Mikroskopische Physiograpliie der Massigen Gesteine' 



3rd ed. pp. 377-80 & 537-46 (1896). 

 [21] Peioe, Gr. T. ' Note on the Occurrence of Rocks allied to Monchiquite in the 



Island of Fernando Noronha ' Min. Mag. (Journ. Min, Soc.) vol. xi (1897) 



p. 171. 

 [22] Ceoss, Whitman. 'An Analcite-Basalt from Colorado' Journ. Geol. Chic. 



vol. V, pp. 684-93 (1897). 

 [23] Washington, H. S. ' Solvsbergite & Tinguaite from Essex County (Mass.) ' 



Am. Journ. Sci. ser. 4, vol. vi, pp. 182-87 (1898). 

 [24] RosENBuscH, H. ' Elemeute der Gesteinslehre ' pp. 233-37 (1898). 

 [25] Beoggee, W. C. 'Die Eruptivgesteine des Kristianiagebietes III : Das 



Ganggefolge des Laurdalits' pp. 62-63 (1898). [In Videnskabsselsk. 



Skrift. 1. mathemat. naturv. Kl. 1897, No. 6.] 

 [26] Lcewinson-Lessing, F. ' Studien xiber die Eruptivgesteine ' Congres G^ol. 



Internat. Compte-rendu Vlleme Sess. (1897) pp. 289-94 (pubd. 1899). 

 [27] Flett, J. S. ' The Trap-Dvkes of the Orkneys ' Trans. Roy. Soc. Edinb. 

 • vol. xxxix, pp. 887-901 (1900). 

 See also [31] p. 191. 



II. Leucite and Pseudoleucite. 



[28] HussAK, E. ' Ueber Leucit-Pseudokrystalle im Phonolith (Tiuguait) der 



Serra de Tingua, Estado Rio de Janeiro (Brazil) ' Neues Jahrb. vol. i, p. 166 



(1890). 

 [29] PiESSON, L. V. ' On some Phonolitic Rocks from Montana ' Am. Journ. Sci. 



ser. 3, vol. 1, pp. 395-96 (1895). 

 [30] Weed, W. H., & L. V. Piesson. ' Missourite, a Nevs^ Leucite-Rock fi-om the 



Highwood Mountains of Montana' Ibid. ser. 4, vol. ii, p. 315 (1896). 

 See also [11] pp. 267-74, 280-81 & 284-85. 



III. Miscellaneous. 



[31] Teall, J. J. H. ' British Petrogi-aphy ' pp. 394-97 (1888). 



[32] . 'On the Amygdaloids of the Tynemouth Dyke' Geol. Mag. p. 481 



(1889). 



EXPLANATION OF PLATE II. 



Fig. 1. Microscope-section of monchiquite from Mount Girnar, Junagarh 

 (Kathiawar) X 18, shovtnng brown hornblende, green augite, and 

 colourless circular areas with interstitial material. 

 2. The same x41, showing a single circular area containing analcime 

 with rectangular cleavage. A portion of a large crystal of augite 

 is seen in the upper right-hand quadrant. 



Discussion. 



Mr. Prior said that, although many may deplore the continued 

 increase of rock-names, yet the use of a new name in the case 

 of the monchiquites appeared to be perfectly justified, since they 

 have such well-marked characteristics, both mineralogical and 

 geological. In Brazil and Canada these rocks are of great age, 

 but in Bohemia they occur in association with Tertiary volcanic 

 rocks. He would be glad if the Author could give some idea as to 

 the age of the Indian rock. He thought that the analytical evidence 

 was not sufficient to support the idea that analcite formed under 

 pressure could contain more potash than ordinary analcite. 



Gen. ]y;cMA.H0N thought that in attempting to decide the question 

 whether the analcime in the monchiquite described by the Author 

 was an original or a secondary mineral, we should give great weight 

 to the probabilities of the case. It seemed to him highly improbable 

 that a hydrous zeolite which contained no less than 8"2 per cent, of 

 water was the product of igneous or aqueo-igneous fusion at the high 

 temperature of molten rock. He thought the probability was that 



