36 PROCEEDINGS OF THE GEOLOGICAL SOCIETT. 



Felixstow, in Suffolk. In 1842 I was much puzzled to account for 

 the nature of these concretions. At a cursory glance one might 

 almost be inclined to pass them by as waterworn pebbles, as they 

 lie abundantly interspersed among the comminuted shells which 

 form the upper parts of the cliffs. I found more than one eminent 

 geologist disposed to agree with me in considering them to be 

 rolled masses of London clay which had been indurated subse- 

 quently to their deposition in the crag. On my again visiting 

 Felixstow during the summer of the present year (1843), I deter- 

 mined to give them a particular examination ; and although a form- 

 ation which has been so thoroughly worked as the crag is not 

 likely to afford a casual visitor the opportunity of gleaning much 

 of novelty, I believe I have satisfactorily ascertained the origin 

 of these concretions, and have added to the list of crag fossils 

 the petro-tympanic bones of at least four species of Cetaceans. 

 These latter, I am persuaded, have been overlooked among the 

 many concretions of this formation. They are, however, of a dif- 

 ferent composition, and closely resemble, in this respect, the silici- 

 fied fragments of bone so abundant in this locality. I believe the 

 specimens I have procured will range under two types, each con- 

 taining at least two species. I am not competent to the task of 

 throwing any osteological light upon these fossils, but am happy to 

 state that Professor Owen has undertaken their examination ; and 

 we may therefore expect before long to be in possession of all that 

 can be said about them. It seems to me not a little remarkable, 

 that all these specimens should have been procured within a very 

 narrow compass, for I found none beyond the limits of two con- 

 tiguous indentations in the cliff, a short distance to the north of 

 Felixstow. 



But, to return to the concretions to which I am more particu- 

 larly desirous of directing attention. They exhibit a very great 

 variety of forms. Many are more or less spheroidal, fusiform, and 

 cylindrical ; many are perfectly amorphous. They appear to be 

 composed of a fine-grained compact ferruginous claystone, of a 

 dark chocolate brown colour ; but the surface, which is very 

 smooth, and even polished, becomes pale by exposure. They often 

 separate by natural flaws into three or more fragments, which are 

 bounded internally by nearly plane surfaces. Many of them offer 

 traces of organic association ; and the result of an extensive ex- 

 amination has convinced me that they must all be considered as of 

 coprolitic origin. I am not aware whether any analysis has ever 

 yet been made of them. 



I will now direct attention to the following peculiarities observ- 

 able in some one or other of the specimens referred to : — 



1. Two spiral masses. 



2. A large perforated one, with traces of spiral or annular transverse convo- 

 lutions. 



3. Other smaller ones, the convolutions being longitudinal. 



4. Common character of the cylindrical and fusiform ones, seen, by fracture, 

 to be formed of longitudinally coiled folds ; with a perforated axis. 



