Vol. 5 I.J ANNIVERSARY ADDRESS OF THE PRESIDENT. lxXVU 



"We may now add yet another locality in which this remarkable 

 fauna occurs, as proved by the presence of the remains of Olenellus 

 and the pteropod Salterella ; namely in Western Australia, where it 

 was discovered by Mr. Hardman in 1886. 1 



I must here refer to the discoveries of the limbs of trilobites. 

 In 1870 the late E. Billings, F.G.S., the Palaeontologist of the Geo- 

 logical Survey of Canada, brought before this Society and described 

 a specimen of Asaphus platycephalus, from the Trenton Limestone 

 of Ottawa, Canada, exhibiting remains of eight pairs of limbs, 

 corresponding with the eight free and movable segments of the 

 body, and showing the hypostome still attached to the doublure of 

 the anterior border of the cephalic shield ; traces of two appendages 

 under the caudal shield were also visible. 



On that occasion I exhibited a specimen of Asaphus from 

 the same locality and horizon, showing evidence of a small 

 7-8-jointed palpus lying at the side of the hypostome apparently 

 in its original position. After some remarks on the superficial 

 characters of trilobites, I added: — 'The prominence of the hypostome 

 in the trilobita reminds one even more strongly of the genus Apus 

 than of the isopods, and it is quite reasonable to expect in the trilobita 

 a more generalized type of structure than that which marks the 

 modern representatives of the class.' 2 



In 1881, after many years of untiring labour, Charles D. 

 Walcott, F.G.S., 3 furnished most conclusive proofs of the existence 

 of appendages to the cephalic, thoracic, and abdominal divisions 

 of Calymene, Ceraurus, and Acidaspis. His researches have 

 been carried on by the method of making thin transverse and 

 longitudinal sections 4 of rolled-up specimens. He has shown 

 that the ventral body-wall of the trilobites was bounded inferiorly 

 by a thin chitinous membrane, which was attached to the 

 lower margin of the dorsal exoskeleton all round. This ventral 

 membrane was supported by calcified arches, which gave attach- 

 ment to the appendages beneath. He further established the 

 existence of a row of articulated cylindrical limbs, on each side of 



1 Geol. Mag. 1890, pp. 98-106, A. H. Foord, on Salterella Hardmani, pi. iv. 

 figs. 1, la, lb, and Olenellus Forresti, ibid. pi. iv. figs. 2, 2 a, 2 b. Lower 

 Cambrian, Kimberley District, Western Australia. 



- Quart. Jom-n. Geol. Soc. vol. xxvi. (1870) p. 488. 



1 In ' Bull. Mus. Comp. Zool. Harvard, vol. viii. p. 6 & pp. 191-224. 



1 Of which he has had over 2000 thin sections prepared. 



