1913.] NATURAL SCIENCES OF PHILADELPHIA. 587 



island of Antigua, which was published in 1885, in the Bulletin 

 du Musee Royal d'Histoire NatureUe de Belgique/-' This paper by 

 M. Purves is much fuller than that by Nugent, and he distinguishes 

 more divisions in the geological formations. The divisions of 

 M. Purves are as follows: 



H. Horizontal marls. 



G. Upper limestones and marls. 



F. Upper tuffs. 



E. Lacustrine or fresh-water chert. 



D. Volcanic sands and sandstones. 



C. Lower limestone or marine chert 



B. Lower stratified tuffs. 



A. Porphyrites and volcanic agglomerates. 



Of these *'A. Porphyrites and volcanic agglomerates" is the 

 No. 1 of Nugent, "trap and trap-breccia" ; "B. Lower stratified tuffs" 

 is the "stratified conglomerate" No. 2 of Nugent; C, D, E, and F, 

 of Purves come in the "chert" of Nugent No. 3, who did not recognize 

 any distinction between the marine and the fresh-water cherts; 

 while divisions G and H of Purves are included in the "marl or 

 calcareous beds," No. 4 of Nugent. Indeed, it is rather doubtful 

 if Nugent recognized the horizontal marls at all. This paper of 

 M. Purves is accompanied by a geological map of Antigua, upon 

 which the divisions which he recognizes are set down, and a geological 

 section from St. Mary's Rectory to Drew's Hill and thence to Hodge 

 Bay is given to show the structure. This map indicates a fault, 

 with upthrow to the northeast and general N. W.-S. E. strike, dis- 

 locating the formations so that D, "the volcanic sands," is brought 

 to the surface and lies next to F, the "upper tuffs." This makes 

 the lacustrine or fresh-water cherts appear at the surface in two 

 bands traversing the island from northwest to southeast. Several 

 minor faults are shown on this map, and I observed a number which 

 have not been mapped. This fault, as indicated by Purves, runs 

 from about ^ mile south of Corbizon Point on the northwest coast to 

 the small bay between Isaac Point and Standfast Point which lies 

 to the southwest of Willoughby Bay at the southeast of the island. 

 It is of interest in connection with the paper by Guppy mentioned 

 below. Each of the eight divisions of the formations of the island 

 enumerated by Purves is described in detail as regards its composi- 

 tion and character, but little information is given in regard to the 



5 "Esquisse geologique de I'lle d'Antigoa." Btill. Mus. Roy. Hist. Nat. Bela.^ 

 Vol. Ill, 1884-85, pp. 273-318. 



