DAVIDSON — ON SOME FOSSIL BRACHIOPODA, 



467 



much resemblance to the one and to the other, but I have 

 deemed it pi-eferable, for several reasons, to retain it, at 

 least provisionally, as a separate species. It v^ill be 

 desirable to assemble a greater number of specimens 

 than I have been able to command, in order to determine 

 the true character of this species. 

 PLAisATA. Phillips, Geol. of York, pi. x., fig. 3, 1836 : and Dav., 

 pi. vii., fig. 25 -- 36. This appears to be a good species, 

 and easily distinguishable. 

 FusiFORMis, Philliijs, pi ix., fig. 10, 11 ; Dav., pi. xiii., fig. 15. Of 

 this only a single imperfect specimen appears to have 

 been discovered (now in the British Museum), so that 

 the -character and value of the species cannot be con- 

 sidered as finally established ; search for more examples 

 is very desirable. 



TFviAiVGCLAKis, Martin, sp , Pet. Derb., pi. xxxvi,, fig. 2, 1809: 

 and Dav., pi. v., fig. 16 — 24 = ornithorhynclia, M'Coy. 



TKiGONALis, Martin, sp., Pet. Derb., tab. xxxvi., fig. 1, 1809: 

 and Dav., pi. v., fig. 25 — 34. 



BisuLCATA, Sow., M.C., tab. ccccxciv., fig. 1, 2, 1825: and Dav., 

 pi. v., fig. 1 : pi. vi , fig. 1 — 19 : and pL, vii., fig. 4 = 

 semicirciilaris, Phillips = calcarata, M'Coy = transiens, 

 M'Coy. ? 



coNVOLUTA, Phillips, Geol. of York., pi, ix., fig. 7, 1836. and 

 Dav., pi. v., figs. 2 — 15 = (?) rliomhoidea, Phillips. I 

 have still some misgivings relative to this species and 

 its supposed synonym ; but three or four true examples 

 of the typical S. convoluta have come under my obser- 

 vation, and it "will be very desirable for us to ascertain 

 whether Phillips' species may not be a very transverse 

 or exceptional condition of Sp. bisulcata, Sow. 



GRANDicosTATA, M'Coy, Brit. Pal. Foss., pi. iii., d., fig. 29, 1855 : 

 and Dav., pi. v., fig. 38, 39, and pi. vii., fig. 7-16. 

 N.B. — All these forms appear to be nearly related. 



LAMiNOSA, M'Coy, Synopsis Carb. Foss. of Ireland, pi. xxi., fig. 

 4, 1844 : and Dav., pi. vii., fig. 17 — 22 = tricornis, De 

 Koninck. This appears to be a very good species, but is 

 rarely found in good condition in our English or Irish 

 localities. 



cuspiDATA, Martin, sp.. Trans. Lin. Soc, pi. iii., figs., 1 — 6, 1796 : 

 ami Dav., pi. viii., 19 — 24: pj. ix., figs. 1, 2 = simplex, 

 M'Coy, not of Phillips. 



DisTANS, Sow., M.C., tab. 494, fig. 3, 1825 : and Dav., pi. viii., 

 fig. 1 — 17. I have never met with any example in which 

 the deltidium was completely preserved, but from the 

 inspection of an internal cast from the dolomitic carbo- 

 niferous limestone of Breedon it would appear that Sp. 

 cuspidata possessed a circular foramen in its deltidium, 

 as in Dalman's Cyrtia, to which these two species pro- 

 bably belong. 



MESOGONIA, M'Coy, Synopsis, pi. xxii., fig. 13, 1844 : and Dav., pi. 

 vii-, fig. 24. This is said by Prof, de Koninck to be a 

 good species, but I have never had an opportunity of 

 studying the shell. 



N.B. — Sp. hicarinata, M'Coy, Synopsis, pi. xxii., fig. 10 : 

 Sp. decemcostata, M'Coy, fig. 9, and Sp. sub-conicus, Martin, 

 Pet. Derb., tab. xlvii., fig. 6-8, 1809, are very doubtful 

 specieS; and cannot be accepted without further research. 



