142 Obituary — Professor H. A. Nicholson. 



tlie same authors, which appeared subsequently, dealt with the age 

 and the fossils in the various formations in the Cross Fell Inlier. 



Professor Nicholson's researches in Invertebrate Palseontology 

 were concerned mainly with Graptolites, Corals, Monticuliporoids, 

 and Stromatoporoids. He first devoted his energies to the Grapto- 

 lites, with which some of the beds in the Lake District are crowded, 

 and described those in the Skiddaw Slates, pointing out their close 

 resemblance to the forms in the Quebec Group of Canada. Then 

 followed papers on Ftilogrnptus ; Helicograptus, a new genus ; the 

 Distribution in time of the British species and genera of Graptolites ; 

 the Graptolites of the Coniston Flags ; British species of Didymo- 

 graptns ; and on the genus Climacograptus, with notes on the British 

 species of the genus. These detached papers were succeeded by the 

 first part of a detailed monograph on the Graptolites of Britain, in 

 which the history, morphology, the nature and functions of the base, 

 mode of existence, geological distribution, and definition of the 

 various genera of the group were ably treated. Further work was 

 interrupted by Nicholson's residence in Canada, and not again 

 resumed (save in a brief but important paper jointly with Professor 

 Marr, dealing with the phylogeny of the group, which appeared in 

 the Geol. Mag., Dec. IV, Vol. II, 1895) ; the task thus relinquished 

 passing thenceforward into the hands of his friend Professor Chas. 

 Lapworth. It is well known that the study of the Graptolites in the 

 rocks of this country is very difficult on account of their compressed 

 condition of preservation, and it required much critical acumen 

 on Nicholson's part to decipher their characters so correctly as he 

 has done. 



The marvellous abundance and variety of forms of Corals and 

 IMonticuliporoids in the Palseozoic rocks of North America induced 

 Nicholson to make large collections of them during his stay on that 

 side of the Atlantic, and they furnished the materials for many 

 years' study after his return. At the time when he began his work 

 on these organisms, the practice of making thin sections to show 

 their interior structure had not come into vogue ; Nicholson was one 

 of the first to appreciate the advantages of this method of investi- 

 gation, so he procured a lapidary's wheel, and with unwearied 

 diligence set himself to make thin slices, in various directions, of all 

 the forms he studied, and then mount them for the microscope. By 

 this means he was enabled to ascertain the real structure of the 

 fossils, and to define their characters with a precision not previously 

 attainable. The fresh knowledge thus obtained of the actual 

 anatomy and systematic relations of the Palseozoic Corals and 

 Monticuliporoids, formed the basis of the two elaborate monographs 

 on these groups, and gave to them a special value and interest. 

 Nicholson's determinations of the systematic affinities of some of 

 these forms were, as he himself acknowledged, of a tentative character, 

 and the tendency of recent opinion with respect to the Monticuli- 

 poroid group is to associate it with the Polyzoa rather than with 

 the Corals, where it had been placed by Nicholson, but this in no 

 wise affects the accuracy of his descriptions and figures of the 

 various forms of the group given in these monographs. 



