440 Rev. R. Ashington Bullen — 



In one small piece which I also owe to Mr. L. L. Mowbray is a cast 

 of Peneroplis pertusus (Fig. 5 text). The specimen from which the 

 cast comes must have been quite unworn and perfect. The position 

 is some 75 feet above O.D., and at a distance of about 580 yards 

 from the present shore on the south side. 



I append the penological report of Mr. Russell F. Grwinnell : — 



"This rock is seen in thin section to be composed of fragments of 

 organisms (preserved in calcium carbonate) which are embedded in 

 a dense grey-brown cement. The organic fragments reach up to about 

 0'8 mm. in greatest diameter. They are very varied in form, and it 

 is impossible to identify many of them (PI. XXIII, Fig. 1). Some 

 may very likely be Bryozoa, others coral. A few pieces are definitely 

 recognized as the calcareous alga Lithothamnion, which is a very 

 well-known form on coral reefs. 



" The dense cementing material is difficult to identify. It may be 

 a calcareous mud, formed of comminuted organic fragments and 

 possibly compacted by a certain amount of secondary recrystallization. 

 If so, this recrystallization has not gone far. The comminution may 

 be due to purely mechanical causes or the material may have passed 

 through the body of some animal, thus being coprolitic. A minute 

 fragment, which was not used in making the thin section, was 

 therefore tested for phosphorus : owing to the small size of the 

 fragment, the test was not decisive,, but it is probable that this 

 element was present. The curious colour of this cementing material 

 in thin section and its apparently fragmental character would suggest 

 a coprolitic origin. 



" Thus rock No. 2 is a clastic rock, made up of organic fragments 

 (of which some are definitely recognized as coral-reef forms, and 

 others may well be so), cemented together by a dense material. This 

 cement probably consists largely of comminuted organic fragments, 

 which have possibly been phosphatized (as well as comminuted) by 

 coprolitic means." 



The puzzle is how the perfect Foraminifer (Text-fig. 5) could 

 have reached a spot so far from its native element and become 

 embedded in what has become hard dense coprolitic rock. 



The explanation perhaps is that the rock was formed in a spot to 

 which sea birds resorted, and their deposit was calcified in later times 

 gradually and slowly, the Peneroplis having been blown thither by 

 the wind uninjured, since it could not have been ingested by any 

 sea bird and remained in so perfect a condition as its cast shows it to 

 have been. It is to be hoped that more of this type of rock may be 

 discovered near the spot, for the rock at the Museum is evidently only 

 a small fragment of a much larger mass. 



The only other alternative is so improbable that it is only needful 

 to mention it, namely, that the specimen is from a deep-sea mud, of 

 which there are soundings from depths of 1,375 to 2,650 l fathoms. 



1 Wyville Thomson (Atlantic, vol. i, p. 99) gives the depths at which such grey 

 mud and ooze occur near the Bermudas : Station xxxi, S. 2,475 fathoms ; 

 Station xxxii, S. 2,250 f. ; Station xxxiv, N. 1,375 f. ; Station xxxvii, 

 E. 2,650 f. ; Station lv, N. 2,500 f. ; Station lviii, E. 1,500 f. The respective 



