4 Introduction. 



of special interest to me, as it proved that iwy conclusion was based upon sound 

 evidence. Eecent " finds "' of almost perfectly preserved Lophogastrids from the Car- 

 boniferous Rocks exposed on the GuUane Shore, East Lothian, by Mr. Macconochie, 

 have placed this correlation beyond all doubt. 



Another advance of marked significance, in the interval referred to, was the 

 discovery of a living representative of a family of fossil Crustacea which occurs in the 

 Scottish Carboniferous Rocks. It was found in a fresh-water lake high up on Mount 

 Wellington in Tasmania, and was fully described by W. T. Caiman, B.Sc.,^ before the 

 Royal Society of Edinburgii in 189G, his description being published in the Transactions 

 of that Societ}- of the following year. 



In dealing with the classification of fossil Crustacea, one is met at the very outset 

 with difficulties, owing to the imperfectly preserved material available, that do not 

 occur to the carciuologist who deals with living forms. One must therefore base the 

 classification upon characters that are fairly shown upon the parts that fossilise most 

 readily — a method which is far from satisfactory. It is therefore most gratifying to 

 be able to work with such splendidly preserved material as is afibrded by the remains 

 of the Lophogastrid genus Tealliocaris, obtained !)}• ]\Ir. Macconochie froni the Car- 

 boniferous Rocks of the GuUane Shore, and the nearly equally well preserved Euphausiid 

 remains of AidJiracophausia from the Cementstone Group of Duns, Berwickshire. In 

 the former case, such delicate structures as eiUs and Ijreeding lamella^ and in the 

 latter, such organs as the I'ow of luminous globules on the trunk and tail and the 

 coupling hooks on the male sexual organs, are well shown. 



The classification here followed is chiefly based upon that adopted by G. 0. Sars 

 in his Report on the Schizopoda of the Challenger Expedition. The Schizopoda are 

 arranged in two great groups, viz.: — (I.) The Mysid Group, including the families 

 Lophogastrida3, Perimecturidaj, Anaspidaj, and Mj'sidaj. (II.) The 

 Euphausiid Group has only one family, Euphausiida;. 



The Lophogastridse are regarded as the culmination of the Mysid Group and 

 as having reached their fullest development in late Palaeozoic time, when they evidently 

 took the place now occupied by the macrurous and anomurous Decapods. At that time 

 they assumed several forms to suit environment, l)ut they underwent no further develop- 

 ment. The recent Lophogastrids are looked upon as having been preserved through 

 having migrated to the deep sea, and, like survivors of ancient families, were evidently 

 not the most specialised members. 



The Perimecturidaj are considered to have branched off from the Mysid stem 



' Trans. Koy. Soc. Edin., vol. xxxviii., page 787. 



