KOKENOSPIRA. 33 



Dimensions. — Height of shell (estimated), about 11 mm. 

 Horizon. — Lower Ordovician : Stinchar Limestone Group. 

 Localitij. — Craighead, Grirvan. 



5. Bucania, sp. 



1873. Bellerophon suhdecussatus (pars), McCoy, Salter, Cat. Cambr. Silur. Foss. Woodw, Mus., 

 p. 68 {non pp. 97, 83), ref. No. Vig-^*. 



Specific Characters. —SheW subdiscoidal, of 3 — 4 transverse whorls in contact, 

 scarcely overlapping, slowly increasing in size to mouth. Umbilicus deep, 

 exposing all inner whorls ; umbilical edge subangular ; umbilical slope rather 

 steep. Whorls wider than high, with gently convex or slightly flattened dorsum. 

 Slit-band narrow, slightlj^ raised. Mouth not expanded, with short, broadly 

 V-shaped dorsal sinus. Surface ornamented with regular fine transverse lines, 

 meeting slit-band at 75° — 90° [with small oval pits Ijetween them?]. 



Dimensions. — Height of shell, about 8*0 mm. ; width near mouth, about 60 mm. 



Horizon. — Middle Bala Beds. 



Locality. — Allt yr Anker, Meifod. 



Remarks. — This specimen, which is in the Sedgwick Museum, is completely 

 distinct from the typical Bellerophon subdecnssatus, McCoy, ^ from the Denbighshire 

 Flags of Llanrwst, described below under the genus Kolcenospira, the wide open 

 umbilicus exposing all the inner whorls, and the ornamentation entirely marking 

 it off. The appearance of pits between the transverse striae does not seem to be 

 due to the texture of the rock, and may l)e an original character, l3ut the imperfect 

 character of the surface (the specimen being an internal cast) renders the true 

 nature of the ornament rather uncertain. If the pitted appearance is trustworth}', 

 we may compare this shell with Bucania punctifrons, Emmons~; the shape and 

 general features of ottr specimen support this comparison, and the whole appear- 

 ance of the shell recalls that species. 



Genus KOKENOSPIRA, Bassler. 



Generic Characters. — Shell globose or subglobose, involute ; umbilicus open, 

 rather large ; aperture not expanded ; lips thin ; dorsal margin deeply excavated. 

 Slit-band wide, flat, elevated, having usually a broad concave space on each side. 

 Surface ornamented with straight uninterrupted revolving lines or ribs, strong 

 on the lateral parts of the dorsum, fine on the slit-band ; transverse growth-lines 

 generally very delicate. 



1 McCoy, ' Syn. Brit. Palaeoz. Foss. Woodw. Mus.,' p. 311, pi. Il, fig. 25a {non fig. 25). 



2 Ulrich and Scofield, op. cif., p. 894-, pi. Ixvii, figs. 41 — 44. 



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