278 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxv. 



richiidae. Later, in their papers on Carboniferous and Permian Ostra- 

 coda, Jones and Kirkby, while maintaining that Beyrichia is the 

 genus under which the majority of the late Paleozoic species with 

 grooved or sulcate valves should be placed, yet thought it necessary 

 to distinguish, first the two groups Beyrichiella and BeyrichiopsisJ 1 

 and a few years later Synaphe. 1 Finally, Jones separated the bino- 

 dose Primitiu' from the more simple types, as Ulrichiaf and the most 

 simple, nonsulcate types, as Aparchites. d 



In 1890 the senior author of the present paper published the first 

 results of investigations begun in the hope that they might end in a 

 complete revision of the American Paleozoic Ostracoda. For vari- 

 ous reasons the realization of this hope has been greatly delayed, and 

 seems yet far in the future. In the first place the effort to procure 

 material for study proved so overwhelmingly successful that the task 

 assumed proportions quite beyond expectations. The unusual diffi- 

 culty of the subject was recognized in the beginning, but with this 

 unsuspected expansion of the material its difficulties seemed to grow 

 greater and greater, while the mere description of the new and the 

 revision of the old species has itself become a formidable piece of 

 work. Another distressing obstacle was the necessity of finding some 

 more accurate and satisfactory yet cheap method of illustration than 

 had been employed hitherto. After long experimentation the writers 

 believe they have finally solved the problem to the extent of offering 

 at least serviceable if not uniformly artistic representations of the 

 ol ijects. However, these difficulties might all have been overcome long- 

 before this had not other more imperative duties consumed by far 

 the greater part of the time that has elapsed since 1800. With this 

 unavoidable drawback even future progress on the monographical 

 treatment of the Paleozoic Ostracoda must necessarily continue to 

 be somewhat sporadic. 



In the first of Ulrich's papers on Ostracoda e six new genera of 

 Beyrichiidse were proposed. All of these, except Jonesella, were 

 based on or include species previously referred to either Beyrichia or 

 Primitia. Thus Tetradella was proposed for the B. complicata 

 group, Ceratopsis for the horned but otherwise similar group typified 

 by B. chambi rsi, Ctt nobolbina for the 11. ciliata group, Drepanella for 

 a mostly undescribed section, but including /'. ric/u/rdsoiti, and Evry- 

 chilina likewise for a largely undescribed group that was thought to, 



«Geol. .Mat,-., ::<l Dec.. III. L886, pp. 4:14, 438. 



6 Carboniferous Ostracoda from Ireland, Sci. Trans. Roy. Dublin Soc. (2), 

 VI. L896, p. L90. 



"Quart. Journ. Geol. Soc London, XLVI, LS90, p. 543. 



-'Ann. and Mag. Nat. Hist. (6), III, 1889, p. 384 



1 New and Little Known American Paleozoic Ostracoda, Journ. Cincinnati Soc. 

 Nat. Hist., XIX, L890-91, pp. L04-137, 173-211. 



