INTRODUCTION. 



In the year 1880/ while aftiiig as Palaiontologist to the Scottish branch of 

 the Geological Survey, I described several species of the higher Crustacea from the 

 Carboniferous Rocks of Scotland, in a memoir communicated to the Royal Society of 

 Edinburgh, by the permission of Sir A. C. Raiiisay, then Director-General of the 

 Survey. Again, in 1 882,' his successor. Sir Archibald Geikie, sanctioned a further 

 contribution to that Society upon the additional remains of higher Crustacea that 

 had been brought to light in the interval from the same rocks. From that time, 

 up to the date of my retirement in 1905, fresh material steadily accumulated till 

 the collection of the Scottish branch of the Survey ' became unrivalled in the amount 

 aiid variety of the remains of the higher Crustacea from the Carboniferous Rocks. 

 Although acting as Paleontologist and taking a special interest in these treasures, I 

 was unable to give the necessary time to the description of the new materials owing 

 to more pressing duties connected with field work ; but I devoted occasional intervals 

 to drawing and studying some of the specimens. My retirement has given me 

 ample leisure for the work, and by the kindness of my old friend and colleague, 

 Dr. Home, the Assistant to the Director in Scotland, and of Dr. Teall, the present 

 Director of the Geological Survey, I have had the great good fortune to be allowed 

 to pursue this research. 



From an examination of the specimen.s collected since 1882, many of which are 

 in excellent preservation, it became evident that the classification of the forms already 

 described, not only by myself but by other investigators, was defective and often 

 erroneous, and that the materials for correctina^ these mistakes were to be found in the 

 collection of the Geological Survey. Nearly all the remains of the higher Crustacea 

 from the Carboniferous Rocks were formerly classed with the raacrurous Decapods, 

 but the preliminary study of the fossils as they accumulated led me to the belief 

 that they have closer affinities with the Schizopods. The publication in 1885 of the 

 report by G. 0. Sars, ou the Schizopoda obtained by the Challenger Expedition, was 



1 Tnius. Roy. Soc. of Ediii., vol. .x.k.k, p. Ts. (1882). 

 ^ IhU., p. 511. (18^s:{), 



