42 Messrs. Jones and Kirkby on Carboniferous Entomostraca. 



ford." Synops. p. 165, pi. 23. fig. 6 ; Local, p. 100 (" Car- 

 boniferous slate and arenaceous limestone," Local, p. 48). Grey 

 limestone, with Spirifer, Crinoids, &c., and some obscure Ento- 

 mostracan valves besides the Bairdia under notice. This is in 

 good preservation. In 1859 one of us carefully examined the 

 specimen, and, having cleared away some of the matrix, con- 

 sidered the carapace to have been sufficiently well shown, and 

 regarded it as being somewhat diflferent from Bairdia plebeia, 

 Reuss, in exhibiting less convexity in the antero-ventral edge. 

 Unfortunately this very convexity could even then have been 

 found by greater boldness of manipulation; for a year after- 

 wards, on again closely examining the specimen, it came out of 

 the stone, quite perfect, showing a fully curved hatchet-edge, as 

 in B. plebeia. 



After the many doubts expressed as to the identity of the 

 Carboniferous B. carta and the Permian B. plebeia, we cannot 

 now recognize (with Sir R. Griffith's specimen clearly before us) 

 a real specific distinction; and B. carta stands as the oldest 

 name. B. plebeia, however, may conveniently remain as a term 

 of inferior grade for the very prevalent form with a rounded 

 antero-dorsal angle (and hence less hatchet-shaped anterior ex- 

 tremity, as depicte4 in Reuss's figure of B. plebeia, Jahresbe- 

 richt Wetterau. Gesell. 1854, p. 67, fig. 5, and in those given 

 in the Transact. Tyneside Field-club, vol. iv. pi. 9. figs. 1, 2, 4, 

 and woodcut 1, p. 145). 



4. "Bairdia gracilis." Synops. p. 165, pi. 23. fig. 7. As 

 we have not seen this specimen, and as it is not referred to in 

 the List of Localities, we have nothing to add to Prof. M'Coy's 

 brief description of it, except that it seems to be the same as 

 B. subcylindrica, Miinster, sp. (Annals N. H. ser. 3. vol. xv. 

 p. 409, pi. 20. fig. 13). 



5. " Cythere amygdalina." Synops. p. 165, pi. 23. fig 8. 

 We have not seen this specimen ; and, not being mentioned in 

 the List of Localities, it has probably been mislaid. We have 

 seen, however, a form corresponding to fig. 8 in the hand-spe- 

 cimen described further on as No. 10. Prof. M'Coy states that 

 " C. amygdalina " is " common." 



- 6. "Cythere arcaata. Yellow Sandstone ; Dromard, Drapers- 

 town, CO. Londonderry." Synops. p. 165, pi. 23. fig. 9 ; Local, 

 p. 48 ("Arenaceous shale," Local, p. 100). A blackish mica- 

 ceous shale, rather hard but fragile, containing Modioli (?), and 

 abounding with small Entomostraca, Leper-ditia subrecta, L. Sco- 

 toburdigalensis, Kirkby a annectens (sp.n.), and others, but nothing 

 corresponding to the figure given of " C. arcaata" which we 

 are inclined to believe to have been a specimen of L. subrecta 

 partially hidden by matrix on its dorsal region. Prof. M'Coy 



