Vol. 56.] AND OLDHAMIA. 275 



placed it with the Hydrozoa, as also did Baily (4, 9, 11) ; while 

 Gdppert (5) was inclined to regard it as a plant, comparing 

 0. radiata with Sirocoleum of Cayenne or Tolypothrioc coactilis 

 of Jutland, and 0. (Murchisonites) antiqua with Liagora lamellosa, 

 a species of Phycaceae. The majority of palaeontologists subsequent 

 to Goppert seem to have accepted his views as to its vegetable 

 nature ; thus Salter (7) concluded that it was a calcareous alga, 

 ' can scarcely be otherwise ' he remarks, and later (10) he cites 

 Dr. Busk and the Rev. J. M. Berkeley as being of the same opinion, 

 which was also shared by Schimper (8). Salter quotes Berkeley 

 as comparing Oldhamia with the Siphonacean alga Acetabularia. 

 Barrois (23) associates it with Chondrites, and as regards the 

 species 0. Rovelaquei in particular he remarks that the regular 

 ramification of the stem and the flabellate arrangement of the 

 appendages forbid a comparison with the tracks left by an animal. 



The first to question seriously the organic nature of Oldhamia 

 appears to have been Rcemer (13), who regarded it as a mere 

 wrinkling of the rock due to pressure ; his words are ' durch Druck 

 oder Zusammenziehung hervorgebrachte Riinzelung oder Faltelung 

 des Thonschiefers.' This view was adopted by Nathorst (14), and 

 later advocated on independent evidence by the present author (19, 

 20), who was not aware that he had been anticipated by Rcemer. 

 Dr. Joly, who was at first disposed to attribute Oldhamia to crys- 

 talline action (18), was afterwards led to change his views, and 

 reverted to the belief in its organic nature ; the present author (24) 

 likewise abandoned his first position, and compared Oldhamia 

 radiata to ' the radiate branched markings which may sometimes 

 be seen on muddy flats, extending from the mouth of the tubes of 

 burrowing worms.' Prof. Bonney (22) had previously urged several 

 weighty objections against the theory of the inorganic origin of 

 Oldhamia (see p. 276). 



On commencing the study of Oldhamia I approached the subject 

 under the impression, which prevailed at the time, that it was the 

 genuine remains of some organism, but since it did not present 

 such characters as might be expected in a hydrozoon or polyzoon, 

 I fancied that it might possibly be some form of calcareous alga. 

 A well-preserved specimen in the Geological Museum of Trinity 

 College, Dublin, seemed likely to throw some light on the question, 

 since it presented, in addition to the usual characters, indications of 

 structure traversing the substance of the matrix. An examination 

 of thin slices under the microscope seemed to show, however, that 

 these appearances were fallacious ; a structure was certainly 

 present, but not of an organic nature, nothing more indeed than a 

 wrinkling of the laminae of the rock. An examination of numerous 

 other specimens led to similar results. It thus seemed definitely 

 proved, that whatever else Oldhamia might be, it certainly was not 

 the remains, or the pseudomorph of the remains of an organism, 

 but merely a marking in the slate. True, such a marking might 

 conceivably be of organic origin, but an explanation which would 



