Palaeozoic B halved Eatomostraca. 175 



At various times the genus has been referred to incidentally, 

 or in general terms, by one of us in papers on Palaeozoic Bi- 

 valved Entomostraca — as in the Proceed. Geologists' Assoc. 

 1869, Palasoz. Entom. p. 8, and in the 'Monthly Micro- 

 scopical Journal,' vol. iv. 1870, p. 192, where a generic de- 

 scription was given, and K. Urei figured (pi. 61. fig. 15) as 

 a representative of it. 



During the whole of this period, from 1859 to the present 

 time, materials and information relating to Kirkbya have been 

 accumulating with us ; and of these ultimately we hope to 

 make full use in our account of the Carboniferous Entomo- 

 straca for the Pakeontographical Society. But in considera- 

 tion of the genus having gradually become important as to 

 the number of its species, as well as being a type of the Os- 

 tracoda especially distinctive of the Carboniferous period, we 

 venture to offer, without more delay, the accompanying brief 

 account of the more important (the majority) of the forms 

 known to us. 



Our knowledge of these forms is greatly due to the help we 

 have obtained, in specimens, from numerous friends and cor- 

 respondents. Among these may be named Mr. John Young, 

 of the Hunterian Museum, Glasgow ; Messrs. David Robert- 

 son, James Armstrong, James Thomson, and others of the 

 same city ; Mr. James Bennie, of the Geological Survey, 

 Edinburgh ; the late Mr. Charles Moore, of Bath, and others. 



Most of our specimens of Kirkbya are from the marine 

 shales overlying, underlying, or otherwise associated with the 

 calcareous beds of the Carboniferous series. In Scotland they 

 are equally common in the Upper and the Lower Limestone 

 series ; and some of the species are found in the thin limestones 

 well down in the Calciferous Sandstones. In England they 

 occur in the marine shales of the Yoredale rocks*, and in 

 the shaly partings of the Scar or Mountain Limestone. 

 The Irish specimens that we have seen are from the Lower 

 Carboniferous Shales. 



We have no examples of any of the species from the upper 

 portion of the Carboniferous series, either Coal-measures or 

 Millstone-grit, although in the Permian limestone, overlyino- 

 the Coal-measures, in Durham and Yorkshire, one species (K. 

 permiana) reappears, and ranges from the lowest beds to near 

 the top of the formation. 



In most cases the individuals of the different species occur 



rather sparingly, or but moderately plentiful, with the Brachio- 



pods, Polyzoans, Crinoids, and other marine fossils usually 



associated with them. This is the rule; but in a few in- 



* G. R. Vine, Proceed. Yorksh. Geol. Polyt. Soc. 1883, p. 2.39 



13* 



