SPIRIPERA. 45 



imperfectly preserved ; but Phillips describes those he has seen and figured as " Concen- 

 trically undulated, with concentric, raised, small ridges, across which run fine, interrupted, 

 longitudinal lines, producing a minute crenulation, or even granulation;" and these 

 markings are, no doubt, due to the concentric spiny fringes which cover the surface of the 

 shell, and which I have already had occasion to describe and illustrate at p. 225, and 

 PI. LI, fig. 15, of my 'Monograph of British Carboniferous Brachiopoda.' One of the 

 specimens resembled Spirifer concentricus, Schnur, from the Eifel. 



Sp. microgramma, Phillips (fig. 16), I have not been able to examine ; and, as the very 

 imperfect figure represents only a portion of one of the valves, it is impossible for me to 

 offer any decided opinion as to its specific claims. I will, however, here reproduce the 

 original description : 



" Character. — Sub -orbicular, rather depressed, with a slight mesial undulation (convex 

 on the lesser valve). Surface thickly and finely striated from the beaks, the striae being 

 crossed by the rather conspicuous edges of many laminae of growth ; at the intersections 

 of these two sets of lines are minute rounded eminences. 



" The analogues of this species are fossils of the Mountain-limestone, viz., Sp. imbricata, 

 Sp. mesoloba, &c. Having collected two agreeing specimens from different districts, I am 

 desirous of calling attention to it, as at least a definite and delicate variety of Sp. imbricata. 

 Loc. — In North Devon— Brushford ; in South Devon — Hope, near Torquay." 



It must be remembered that I have already shown, at p. 64 of my ' Carboniferous 

 Monograph,' that Sp. imbricata and Sp. mesoloba are synonyms, or simple modifications in 

 shape, of Sp. lineata, and that we are, therefore, so far justified in provisionally locating 

 Phillips's so-termed species among the synonyms of Martin's shell. 



interval, as in the following scheme (the Barnstaple group being omitted, as belonging to the Carboni- 

 ferous rather than to the Devonian system, or, perhaps, forming passage-beds between the two). 



CARBONIFEROUS. 



< 



O 

 > 



ft 



£ 



ft 



O 



Petherwin beds. 



Dartmouth or Upper Slates : the " Dartmouth " group may be on the horizon 

 of the "Petherwin" series, but it is not easy to determine this point, as the 

 former has yielded but few fossils. 



Torquay or Limestone beds. 



Meadfoot or Lower Slate, and Upper Old Red. 



Middle Old Red. 



Lower Old Red. 



UPPER SILURIAN. 



And that it may be true that " nobody has ever yet described any place where the South Devon beds 

 lie above rocks which contain undoubted Upper Silurian," and below others containing Carboniferous 

 Limestone fossils ; but that surely we must not expect to find an unbroken sequence everywhere. 



