46 THE APPENDAGES, ANATOMY, AND RELATIONS OF TRILOBITES. 



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THE APPENDAGES OF KOOTENIA. 



Kootenia dawsoni Walcott. 

 Illustrated: Walcott, Smithson. Misc. Coll., vol. 67, 1918, pi. 14, figs. 2, 3. 



One specimen figured by Doctor Walcott shows the distal ends of some of the exopo- 

 clites and endopodites of the right side. He compares the exopodites with those of Nco- 

 lenus, stating that the shaft consists of two segments, the proximal section being long and 

 flat, fringed with long setae, while the distal segment has short fine setje. The endopodite 

 best shown is very slender, and the segments are of uniform width and only slightly longer 

 than wide. 



Measurements (from Walcott's figures) : Length of specimen, about 41 mm. Length 

 of five distal segments of an endopodite, 7.5 mm. Since the pleural lobe is only 7 mm. 

 wide, the endopodites, and probably the exopodites also, must have projected a few milli- 

 meters beyond the dorsal test when extended straight out laterally. 



Formation and locality: Burgess shale, Middle Cambrian, on the west slope of the 

 ridge between Mount Field and Wapta Peak, above Field, British Columbia. 



THE APPENDAGES OF CALYMENE AND CERAURUS. 

 HISTORICAL. 



All of the work on these species has been done by Doctor Walcott, who summarized 

 his results in 1881. 



In the first of his papers (1875, p. 159), Walcott did not describe any appendages 

 but paved the way for further work by a detailed and accurate description of the ventral 

 surface of the dorsal shell of Ceraurus. He demonstrated the presence in this species 

 of strongly buttressed processes which extend directly downward from the test just within 

 the line of the dorsal furrows. One pair of these is seen beneath each pair of the gla- 

 bellar furrows, each segment of the thorax has a pair, and there are four pairs on the 

 pygidium. He pointed out also that these projections- were but poorly developed on that 

 part of the glabella which is covered by the hypostoma. He called them axial processes, the 

 only name which appears to have been suggested thus far. 



The first announcement of the discovery of actual appendages in Ceraurus and Calym- 

 ene was made by the same investigator in a -pamphlet published in 1876 in advance of the 

 28th Report of the New York State Museum of Natural History, the publication of the 

 whole report being delayed till 1879. The results were obtained by the process of cut- 

 ting translucent slices of enrolled trilobites derived from the Trenton limestone at Trenton 

 Falls, New York. Since he summarized all the results of this study in one paper at a 

 later date, it is not necessary to follow the stages of the work. 



A second preliminary paper was published in pamphlet form in September, 1877, and 

 in final form in 1879, when the first figures were presented. 



In his important paper of 1881, Walcott reviewed all that was known of the appen- 

 dages of trilobites to that time, and gave the results of seven years of study of sections of 

 enrolled specimens. Slices had been made of 2,200 individuals from Trenton Falls, which 

 resulted in obtaining 270 which were worthy of study. Of these, 205 were from Ceraurus 

 pleurexanthemus, 49 from Calymcnc senaria, n from Isotelus gigas, and 5 from Acidaspis 

 trentonensis. 



