242 BULLETIN OF THE 



indicate something with regard to relative ages. The eflfnsives are fine- 

 grained olivine diabases, in which the augite crystals are much decom- 

 posed. The freshness of the dike rock would indicate that it is much 

 younger. 



Most of the basic dikes of the Eastern United States previously 'de- 

 scribed, and having a near relation to the above, have been Campton- 

 ite ; in Northern New Jersey, however, some dikes have been noted by 

 Prof. J. F, Kemp,^ which he decides are practically identical with the 

 Ouachitite of Arkansas, and with the Ouachitite the relation of the Con- 

 necticut dike is close. If this Triassic dike rock is finally placed in the 

 Fourchite group, it will be the second occurrence outside Arkansas of 

 the rocks of the group. 



1 Arkansas GeoL Survey, Ann. Rep., 1890, VoL II. p. 403. Also Am. Jour. ScL, 

 April, 1893. 



Petrographical Laboratory, Harvard University, 

 June, 1893. 



DESCRIPTION OF THE PLATE. 



Reproduced by the artotype process from a micro-photograpli taken with polar- 

 izer only. The enlargement is 23 diameters. 



The plate shows an angite phenocryst having a border of secondary augite and 

 enclosing a resorbed grain of hornlilende of the first generation. A portion of a 

 resorbed hornblende cr^ystal of the second generation is also shown. Some of the 

 larger augite crystals of the groundmass are distinguishable. 



