88 ORDOVICIAN AND SILURIAN BELLEROPHONTACEA. 



in the same Museum to which Wyatt Edgell 1 attached the MS. name of Bellerophon 

 discus, but it probably is referable to the genus Zonidiscus rather than to Oxydiscus 

 (see p. 74). It seems to resemble in general characters the shell called Oxydiscus 

 annularis, Perneiy from Stage Ee 2 in Bohemia. 



Addendum. 

 Salpingostoma shallochense, sp. nov. Plate XII, fig. 6. 



Specific Characters. — Shell composed of few whorls in contact but not over- 

 lapping, slowly increasing in size to mouth, circular or subcircular in section, but 

 with dorsum of last whorl weakly carinated towards mouth. Outer whorl 

 ornamented with transverse ruga? set some distance apart and slightly arched back 

 in middle so as to form a wide angle on the dorsum, which shows distinct traces of a 

 median slit with compressed, somewhat sinuous (?) edges. Mouth suddenly and 

 immensely expanded nearly at right angles to plane of shell, forming a trumpet- 

 shaped subcircular peristome with flattened lips about five times the diameter of 

 outer whorl; inner lip reflexed and descending below base of whorls; outer lip 

 entire, without median emargination, but with faint median ridge on its outer 

 surface in continuation of dorsal slit on last whorl. Surface of peristomal 

 expansion marked with low concentric growth-ridges and ornamented with 

 numerous radiating thick rounded raised lines, mostly equidistant and regularly 

 disposed, minutely wavy on the inner and lateral portions, with the broader inter- 

 spaces occupied by 4 — 7 much finer similarly wavy thread-like radial lines. Inner 

 surface of peristome showing numerous fine straight radiating striae and a few 

 concentric growth-ridges. 



Dimensions. — Height of shell before oral expansion, c. 25 mm. ; width of 

 mouth, liO-65 mm. ; height of mouth, 50-55 mm. 



Horizon. — Whitehouse (iron p. 



Locality. — Shalloch Mill, Girvan. 



Remarks. — The cast and impression of the huge mouth of this shell, with a 

 portion of the coiled whorls attached, has been lately sent me by Mrs. Gray. 

 Unfortunately there is not sufficient of this imperfectly preserved specimen to 

 give as full a description of the specific characters as could be desired, but the 

 species is certainly distinct from any previously described, although it is obviously 

 allied to 8. grande (Barr.) 3 from Stage D 5 in Bohemia, agreeing with it in the 

 ornamentation of the peristome, the transverse ribs on the whorls, and the 

 dorsal slit. 



» Ibid., p. 67. 



2 Peruer, op. cit., p. 74, pi. lxxxvi, figs. 1 — 3. 



:i Ibid., p. 97, pi. lxxxiv, figs. 12—14; pi. l.wxv, figs. 22—32 ; text-fig. 69 a—f. 



