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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 79 



to our knowledge in a general way resembles it is the grotesque 

 Bostrichopus antiqyms Goldfuss of the lower Carboniferous (Culm.) 

 of Nassau, Germany. (See fig. 1.) The one specimen known to 

 have been found is preserved in the Bonn collection. Good figures 

 are given in part 1 of Eoemer's Lethaea geognostica (1876), pi. 38, 

 figs. lOa-b, and recently (1929) Steinmann has redescribed it, giving 

 a restoration. According to Goldfuss's figure tliis minute crustacean 

 is surrounded by a corona of 60 extremely thin, flexuous, filamen- 

 tous appendages, radiating from three (or four?) short basic ap- 

 pendages, located behind the head. Steinmann reconstructs the 

 form as having the filamentous feet distributed evenly in pairs on 

 the segments of the body and concludes that the species belongs to 

 an entirely extinct class of crustaceans. Even though the swimming 

 feet have a similar structure, our species is still different in the form 

 of the body, especially of the head, which bears two large eyes in 

 Bostrichofus. 



FiGUP.B 1. — Bostrichopus antiquus Goldfuss. Right figure, 

 entire specimen, natural .size ; left, enlargement of body 

 and bases of limbs. (After Roemer) 



The outstanding characters of Marria are the very simple body 

 and the enormous development of the antennae (see postea), which 

 indicates an extreme adaptation of an otherwise primitive form. 



The great age of the form and the fact that a similar development 

 of the antennae (at least of the second pair) takes place in at least 

 twOi orders of the Branchiopoda, namely, the Phyllopoda and the 

 Cladocera, as well as in the next order, the Copepoda, make it proba- 

 ble a priori that the species represents a generalized type, not 

 directly referable to any of the recent orders of crustaceans. Posi- 

 tive determination of its relationship is prevented by the fact that 

 the mandibles and maxillae remain unknown and that the subdivi- 

 sions of the body can not be definitely made out. How uncertain are 

 the determinations of Cambrian crustaceans from incomplete re- 

 mains is clearly evidenced by the fact that Walcott's determinations 

 of the Burgess shale crustaceans were challenged by Fedotov (1925) 

 and Fedotov's in turn by Henricksen (1928). 



