76 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
The Moneague Formation, — The Montpelier beds grado up into more 
massive limestones, white in color, firmer in texture, often semi-crystal- 
line, sometimes containing casts of fossil mollusks and solitary corals, 
and occurring in well defined bands of stratification from one to five 
feet in thickness. More massive texture and regular bedding especially 
distinguishes this formation from the other white limestones of the 
island, such as the chalky rocks of the underlying Montpelier and the 
irregular lumpy texture of the overlying Cobre formations. These rocks 
contain many cavernous moulds of Mollusca and single corals, indicating 
that a considerable amount of shell débris may have accompanied their 
original deposition. The fossils obtained near Ewarton, Retreat, and 
Cinnamon Hill, in a firm Jimestone matrix, were mostly poorly pre- 
served moulds of corals and mollusks, which the paleontologists could 
not determine. 
These rocks become very cavernous through interstitial solution and 
the surface is usually indurated and karrenfeldate. Sometimes the 
limestone is in small angular fragments or lumps with sharp edges, as 
if it had been shattered by some great stress, — a condition which may 
in part be due to shearing, but is also largely produced by irregular 
consolidation and solution. This angular aspect is well shown on the 
right hand side of Plate XXVI. 
Ficurn 24. — Residual Clays in Limestone Sinks at Frankenfield. 
In places the Moneague formation weathers into a yellow ferruginous 
clay subsoil, constituting a thick surface coating. This is the residual 
clay and iron which remains after the transportation of the soluble lime 
by water. Exposures along the railway between Porus and Ipswich 
show some beautiful subaerial alteration. Deep natural wells or pits 
are seen in the limestone. "These are filled with the residual clay, 
similar to the occurrence previously shown in my report on Cuba. 
Where the soils of these limestones have been oultivated the ruinate is 
1 Notes on the Geology of Cuba. — Bull. Mus. Comp. Zool. at Harvard College, 
Vol. XVI. No. 15, 1875, Plate L Fig. 7. 
