98 Prof. AV. J. Sollas. Investigation of Fossils. [May 19, 



8 Kriiger, W., " Beitrage zur Kenntniss der Organismen des Saftflusses der 

 LaubbaiTme," Zopf 's ' Beitrage zur Physiologic niederer Organismen,' vol. 4, 1894. 



9 Karsten, &., ' Ueber farblose Diatomeen,' Flora, vol. 89. Ergaimmgbd. 



1901. 



10 Dangeard, "Kecherches sur lea Eugleniens," ' Le Botaniste,' vol. 8, 1902. 



11 Pfeffer, "NV., 'Text-Book of Vegetable Physiology,' English Trans., vol. 1, 

 1900, p. 430. 



" A Method for the Investigation of Fossils by Serial Sections." 

 By W. J. SOLLAS, D.Sc., LL.D., F.E.S., Professor of Geology 

 and Paleontology in the University of Oxford. Pteceived 

 May 19, Read June 11, 1903. 



(Abstract.) 



Mechanical difficulties preclude the study of fossils by serial thin 

 slices, but serial polished surfaces may be obtained at any desired 

 degree of proximity, and these, when the fossil and its matrix offer 

 sufficient optical contrast, serve most of the purposes of thin slices. 

 They may be photographed under the microscope, so as to furnish a 

 trustworthy and permanent record. The sections may be used to 

 obtain reconstructions of the fossil in wax. Several fossils have been 

 successfully studied in this way : such as Palafospondylus G-unni, Ophinra 

 Egertoni, Lapu'orthwa Miltoni, Monographs priodon and Pakeodi#ru* 

 ferox. The sections are obtained at regular intervals, usually of 

 0-025 mm., by means of an apparatus designed for the purpose by the 

 Kev. F. Jervis-Smith, F.R.S., Reader of Mechanics in the University. 



"An Account of the Devonian Fish, Palceospondylm Gunni, 

 Traquair." By W. J. SOLLAS, D.Sc., LL.D., F.R.S., Professor 

 of Geology and Palseontology in the University of Oxford, 

 and IGEKNA B. J. SOLLAS, B.Sc., Lecturer in Zoology, 

 Newnham College Cambridge. Received May 19, Ptead 

 June 11, 1903. 



(Abstract.) 



This fossil, which has been variously referred to an alliance with 

 Lampreys, Tadpoles, and Lung-fish, has been successfully studied by 

 means of serial sections. The ventral surface of the head bears four 

 pairs of branchial bars, with the last of which two post-branchial 

 plates, the so-called " post-occipital " plates, are associated ; in front of 

 the branchial bars are two pairs of structures, which are regarded as 

 representing the lower jaw and hyoid ; they are supported by u 



