Palaeozoic Bivalved Entomostraca. 183 



The medio- dorsal portion of the valve is depressed, and in 

 front is a rounded boss-like lobe, and behind is another lobe 

 or tubercle, usually smaller than that in front ; the ventral 

 portion of the valve is swollen, and traversed longitudinally 

 by a curved ridge or rib. Lateral contour subcuneiform. 

 Shell rather thin. Surface smooth so far as known. Leno-th 

 3V inch. Edge view (figs. 7 b, c, and 8 b, lateral contours) 

 compressed, ovate. 



The above description applies more correctly to the Irish 

 members of this species. Scotch examples show some differ- 

 ences ; instead of two lobes or tubercles they sometimes have 

 three, either all on the dorsal region of the valve or with the 

 middle one rather lower down than those at the ends and 

 two (or at times three) strong ridges sweep across the valve 

 concentrically with the extreme and ventral borders ■ the 

 uppermost of these is occasionally fully above the median lino 

 of the valve, and the lowermost often takes the form of a 

 marginal rim. The surface also, in some examples at least 

 is reticulated. It may be that these specimens represent a 

 Scotch form specifically distinct from the others. This is a 

 point for further investigation. For the present we designate 

 it K. annectens, var. bipartita. 



The Irish specimens we have seen were collected and 

 submitted to our inspection by the late Sir Richard 

 Griffiths. They are very uniform in character, all of them 

 having the two bosses or tubercles, one towards each extremity 

 of the valve, and but a single ventral rib. They have 

 rather a Beyrichian look, and undoubtedly come nearer that 

 genus than other members of the group under description. 



Localities. — Ireland. In Lower-Limestone Shales Dru- 

 mard, Londonderry ; Cultra, Down ' } Larganmore, Mayo. 



Scotland. Carboniferous Limestone (Lower) : Brocklev 

 Lanarkshire ; Orchard, Gare, in Lanarkshire ; River Avon 

 below Kinneil Mill, Linlithgowshire. 



England. Hurst, near Richmond (bipartita), Yorkshire on 

 the authority of Mr. G. R. Vine (Proc. Yorksh Geol 

 Polyt. Soc. 1883, p. 237). 



Dr. C. W. Giimbel's Kirkbya alptna, figured in his i Kurze 

 Anleitung zu geol. Beobacht. in den Alpen,' 1878, p. 83 

 fig. 28, has a distant resemblance to K. annectens, but is' 

 much more like Beyrichia arcuata (Bean), as far as the little 

 woodcut shows. It is from the Bellerophon-limestone a 

 passage-bed from the Palaeozoic to the Mesozoic (between the 

 Permian and the Trias). 



