80 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



Mollusca occur in these beds. The lumps in the marl are largely fossils ; 

 three specimens are Echinoids, and one is a large Conus, two inches long. 

 Casts of Natica and Cjpraea were also recognized, as well as two species 

 of coral, — one a simple form, the other a compound form, but both so 

 poorly preserved as to be indeterminate. None of these forms suggest 

 the Bowden fauna except the simple coral, and probably they represent 

 a slightly earlier and preceding horizon. 



From Bog Walk Station to a point where the highway to Linstead 

 crosses the railway track, one and a half miles due north, following the 

 south margin of the V)asin valley, the surface exposures consist of later al- 

 luvium. At the last mentioned point the railway cuts through an inlier 

 of white limestone of the Cobre type. This exposure contains an abun- 

 dant molluscan fauna, but all the specimens are poor casts, among which 



c 



Figure 25. Section of Northern End of Bog Walk Canyon. 



1. White stratified Cobre Limestone with Marl Pit. 



2. Conglomerate of small Igneous Pebble. 



3. Buff colored Limestone, banded. 



4. Buff, granular, laminated Marl, with little Conglomerate, oxidizing Red. 



5. An Outlier to North of this Locality, which will be described later. 



the genera Bulla, Area, Cardium, and Lucina are evident. No corals or 

 Echinoids were found. A few miles farther, at Linstead, the Moneague 

 beds appear, apparently beneath this section. The aggregate thickness 

 of the limestone of the Cobre section cannot be less than 1,000 feet, and 

 is probably much more. 



Tiie extent of the Cobre formation is not completely determined. We 

 have personally seen the formation only on the south side of the central 

 portion of the island. Good exposures of it are seen in Clarendon along 

 the highway from May Pen Station, on the Montego Bay Railway, and 

 Cliapelton. Here the limestone has the same general character as that 

 of the Bog Walk section, and constitutes tlie summits of the Minho 

 ^lojintains. Between tlie iMinho liiver and Betreat," the limestone is 

 underlain by more massive bedded layers resembling the Moneague for- 



' Kcliinolnmpas or B. thiiopygua. 



2 Not to bo confused witli Retreat in Trelawney, previously mentioned in dis- 

 cussing tlic Brownstown formation. 



