TREMATONOTUS PORTLOCKI. 83 



It is possible that several varieties are included under the specific name Tr. 

 dilatatus; but the evidence is hardly sufficient to separate them satisfactorily, 

 except in the case of the form from Woodland Point described below. The 

 specimen [280G0] from the Upper Llandovery of Bog Mine, Shelve, may belong to 

 a distinct variety, but is too poor for description. 



3. Trematonotus dilatatus, var. nov. girvanensis. Plate XIII, figs. 2, 3. 



Varietal Characters. — This shell, of which the types occur in Mrs. Gray's 

 Collection, agrees with the type-form in general characters, bill the umbilical 

 edges seem to be subangular, and the oval aperture subcircular or transversely 

 elliptical in shape, the upper lip being less high and the lower lip especially 

 narrower, for it only descends about one-fourth the distance from the base of the 

 mouth to the base of the shell, and therefore does not reach the centre of the 

 umbilicus. The foramina along the middle line of the dorsum also are smaller, but 

 in no case are they well preserved. The whole shell seems more globose and 

 the whorls relatively broader than in the type; but owing to crushing and 

 distortion of the specimens this may be more apparent than real. 



Dimensions. — Height of shell (with oral expansion), 67 mm. ; height of ditto 

 to base of mouth, 27 mm. ; width of mouth. 64 mm.; width of outer whorl at base 

 of mouth, 21 mm. 



Horizon. — Saugh Hill Group, Llandovery Series. 



Locality. — "Woodland Point, Girvan. 



4. Trematonotus portlocki, sp. nov Plate XIII, fig. 4. 



1843. Bellerophon dilatatus, Sowerby, var., Portlock, Geol. Eep. Londond., p. 398, pi. xxix, fig. 1. 

 1875. Bellerophon dilatatus, Sowerby, Baily (pars), Charact. Brit. Fossils, vol. i, Palseoz., p. 65 (non 

 pi. xxii, figs. 1 a, 1 b). 



Specific Characters. — Shell of few volutions; whorls low, transverse, wider than 

 high, with broad gently convex dorsum ; umbilicus large, open, exposing inner 

 whorls (?) ; umbilical edges angular or subangular. Median band narrow, 

 flattened, slightly raised, continuous, bearing small oval contiguous foramina (?). 

 External surface of dorsum ornamented with closely-placed thick revolving lines, 

 20—24 on each side of slit-band, decussated by fine closely-placed transverse lines. 

 Mouth abruptly expanded to a great size, being in height more than twice the 

 diameter of the shell, subcircular in shape, rather higher than wide, with slight 

 dorsal emargination and with whole margin reflexed and flattened, but not covering- 

 last whorl in front, wider dorsally than laterally, and marked with concentric striae ; 

 whole interior of mouth ornamented with closely-placed thick revolving lines 



