78 bulletin: museum of comparative zoology. 



With the probable exception of the Mile Gully ridge, nearly the whole 

 surface of the northern half of Manchester Parish, as crossed in a north- 

 west and southeast direction by the Jamaican Eailway line, between 

 Porus and Phoenix Park, is composed of the stratified beds of the 

 Moneague formation similar to the exposures at Ipswich, and consists 

 of alternations of hard compact limestone, dull gray-white in color, semi- 

 crystalline in texture, with alternations of white calcareous chalky marls. 

 The beds are quite cherty in places, which, with their stratigraphic prox- 

 imity, suggest the nearer relationship of these beds to the Montpelier 

 than to the Bowden formation. Casts of fossil Mollusca and small 

 sin*de stems of branch coral like those found at Petreat also occur. 

 These beds are especially well displayed in the cuttings of the river 

 near Williamsfield. 



At Ewarton the railway terminal is quarried out of the beds which 

 occur in massive uniform layers several feet thick. A few molluscan 

 fossils weather out upon the surface of the rocks, but they are too indis- 

 tinct for identification. From Ewarton to Moneague the beds can be 

 seen from the highway, arching over the western border of the St. 

 Thomas basin. At Moneague they have wide surface development, 

 especially to the westward via Brownstown, Stuart Town, and Retreat. 

 At Ipswich and thence on towards Catadupa the regular bedding is 

 beautifully seen in the deep railway cuttings, as shown in Plates XXV. 

 and XXYI. 



We are not prepared to state positively that the beds of these differ- 

 ent localities are identical, for paleontologic material is very rare, but 

 from their resemblance we incline to think that future research will 

 show them all to be parts of the same formation. 



The Cohre Formation. — Between the town of Bog Walk,^ on the south 

 side of the interior basin valley of St. Thomas-in-the-Vale, and Spanish- 

 town, on the Liguanea Coastal Plain, the Rio Cobre cuts a canyon through 

 a wliite limestone plateau separating the two localities. This canyon, 

 known as Bog Walk, is one of tlie great scenic features of Jamaica, and 

 terminates at the Liguanea Plain as a true boca,^ from which it took 

 its original name, Boca del Agua. 



The canyon of the Cobre is about 200 to 300 feet deep, with sloping 

 sides, a fine view of which is shown in Plate X. ; it is cut entirely out 

 of certain problematic beds of white limestone, which will be described 



' Enjxlish corniptinn of Boca del Ac:\in. 



"^ Among other uses Boca is appUed to the mouth of a canyon debouching upon 

 a phiin. 



