6o2 SCIENCE PROGRESS 



and delicate to have left even their impressions." Linne 

 in 1759 observed what he took to be antennae in a specimen of 

 the genus Parabolina ; but these objects have been shown by 

 C. E. Beecher (1896) to be portions of the anterior border of 

 the head-shield. Had this apparent discovery by Linne been 

 established, it would have saved a good deal of discussion as to 

 whether trilobites were Crustacea or arachnida, since the mem- 

 bers of the latter class, which includes the heavily shielded 

 king-crab, possess neither antennse nor antennules. 



In 1864 E. Billings, of the Geological Survey of Canada, 

 brought to the notice of the Natural History Societ3'- of Montreal 

 a specimen of Asaphits platycephaliis {Isotelus latus Raymond), 

 from Ordovician limestone, on the under side of which clear 

 traces of limbs had been preserved. This was excellently 

 figured in his paper published by the Geological Society of 

 London in 1870, and Henry Woodward, in the discussion then 

 aroused, suggested that the rarity of limbs in connection with the 

 remains of trilobites might be due to the fact that the majority 

 of the fossils were merely cast-off carapaces. 



Six years later, C. D. Walcott, who is still indomitable in 

 adding, month by month, to our knowledge of early forms of 

 life, attacked the problem of appendages in trilobites by cutting 

 thin translucent sections across rolled-up specimens of Calymene 

 and Ceraurus. These came from the Trenton (Upper Ordovi- 

 cian) Limestone of the eastern United States ; but the genus 

 Calymene is familiar to British collectors, in a rolled up or ex- 

 tended condition, from the beautifully preserved specimens in 

 the Gotlandian limestone of Dudley. Walcott cut slices of more 

 than 2,000 individuals, and published his results in a memorable 

 paper in 1881 (" The Trilobite : new and old evidence relating 

 to its organisation," Bull. Mits. Cotnp. Zoology, Cambridge, Alass., 

 vol. 8). He was able to show that Calymene possessed 26 pairs 

 of appendages, four being in the head-shield region, thirteen on 

 the body or thorax, and nine on the pygidium. In addition, 

 one slice gives evidence of the presence of antennules ; but these 

 are now much better known in other genera. 



The long story of patient research now well rewarded is 

 given us in detail by Prof. P. E. Raymond of Harvard University 

 in the monograph already mentioned (" The Appendages, Ana- 

 tomy, and Relationships of Trilobites, "Mem. Connecticut Acad, of 

 Arts and Sciences, vol. 7, Dec. 1920, price $6). He tells how in 

 1892 a bed of black shale, the Utica Shale, which follows on the 

 Trenton Limestone in the Upper Ordovician series, was dis- 

 covered at Rome, New York, crowded with trilobites of the 

 genera Triarthrus, Cryptolithus, and Acidaspis. The structure 

 of the fossils had been exquisitely preserved by replacement with 

 pyrite (iron disulphide), and on thousands of these specimens 



