178 SUPPLEMENT TO THE 



87. Orthis RUSTicA, Soiv. Dav., Sil. Mon., PL XXXIV, figs. 13—22. 



This fine species has been fully described and illustrated at p. 238 of my ' Silurian 

 Monograph,' and all I desire to record here is that it has been found by Mrs. R. Gray in 

 the Upper Llandovery or Penkill Beds in Penwhapple Glen, Ayrshire, also in the same 

 formation at Cuddyston Glen. The variety ri(/ida has been likewise collected by the 

 same lady in the Middle Llandovery at Woodland Point, in Ayrshire. 



88. Ortiiis Sowerbyana, Dav. Sil. Mon., PI. XXXV, figs. 27—31. 



I have nothing to add to the description I have given of this species at p. 247 of my 

 * Silurian Monograph,' further than that the fossil was found by Mrs. R. Gray in the 

 Upper Caradoc at Thraive, and in the Middle Caradoc at Shallock Hill, near Girvan . 

 Some specimens likewise, which I cannot distinguish from it, were also procured by Mrs. 

 R. Gray from the Llandeilo at Craighead and Balcletchie, in Ayrshire. If these last 

 are really referable to the species under description, the shell must have ranged from the 

 Llandeilo to the Lower Llandovery. 



89. Orthis elegantula, Balman. Dav., Sil Mon., PL XXVII, figs. 1 — 9. 



This well-known species appears to have had a considerable vertical range. In 

 Scotland it was found by Mrs. R. Gray in the Llandeilo or Balcletchie Conglomerate, 

 near Girvan, in the Middle Caradoc at Shallock Mill, in the Upper Caradoc at Drummuck, 

 in the Middle Llandovery at Woodland Point, and at Penkill and Bargany-Pond Burn 

 in the Upper Llandovery, all in the Girvan District of Ayrshire. It is plentiful also in 

 the Wenlock series of the Pentland Hills, near Edinburgh. This shell may sometimes be 

 confounded with imperfectly preserved examples of Ortlds testudinaria. 



90. Orthis testudinaria, Dahnan. Dav., Sil. Mon., PL XXVIII, figs. 13—24, Vol. 



IV (Bud. Salt. Mon.); PL XLII, fig. 26; Sil. 

 Sup., PL XIII, figs. 30, 31. 



Specimens which I cannot distinguish from Dalman's types have been found by Mrs. 

 R. Gray in the Llandeilo at Balcletchie and Craighead, Girvan, in the Middle Caradoc 



