LOWER PALAEOZOIC HYOLITHID^E FROM GIRVAN. 205 



Barrande with the operculum in place. In these the apex of the cone is always 

 nearer the ventral side of the shell ; but Salter regarded it as nearer the dorsal side, 

 thus reversing its relations. Barrande's orientation is here followed. 



Hyoliihes asteroideus, sp. nov. (PI. I. figs. 7 -9a.) 



Shell straight, gently tapering at about 1 in 5. Ventral face moderately convex, 

 weakly angulated in centre and obscurely on each side near lateral edge, so that it shows 

 two pairs of flattened surfaces, of which the median pair is the wider. Dorsal face 

 weakly convex. Lateral angles subacute. Section plano-convex. Mouth oblique, with 

 strongly arched, high dorsal lip. Ventral face with one faintly impressed longitudinal 

 line along median keel, and traces of very delicate longitudinal striae over rest of 

 surface, which is also crossed by more or less developed growth-ridges and striae. 

 Dorsal face with strongly arched transverse growth-striae, most marked near mouth ; 

 (longitudinal striae absent ?). 



Horizon and Locality. — Starfish Bed, Drummuck Group, Thraive Glen. 



Remarks. — Only imperfect shells of this species are known, but the formation of 

 the ventral face is characteristic. One fragment with an apertural diameter of 9 mm. 

 has a length of 20 mm., and the shell, when complete, must have measured about 45 mm. 

 Eichwald's H. acutus* from the Orthoceras Limestone, has a somewhat similar shape 

 and cross-section, but the ornamentation is different. t H. elegans, Barr.,| from 

 Stage D, Bohemia, is certainly allied to our species. 



Hyolithes candidus, sp. nov. (PL I. figs. 10-13.) 



Shell straight, short, broad, tapering at about 1 in 2^. Dorsal face divided longi- 

 tudinally into three areas, the lateral ones, which are each about one-quarter the width 

 of the whole face, being flattened, gently inclined, and ornamented with 4-6 strong 

 raised longitudinal lines ; the median area is of twice the width, slightly concave Or 

 flattened, with very fine transverse arched striae and very delicate longitudinal striae, 

 producing a minute cancellation of the surface. Dorsal lip of the mouth strongly 

 arched. Ventral face rounded, gently convex, with rather distant fine longitudinal 

 lines, about 20-25 in number, crossed by much more numerous transverse growth-lines. 

 Lateral angles obtuse, rounded. 



Dimensions : — 



Length ........ 11-5 mm. 



Width of mouth . . . . . . . 4-5 „ 



Horizon and Locality. — Whitehouse Group, Whitehouse Bay. 



Remarks.— This species is rather imperfectly known, being based on the one 



* Eichwald, Leth. Ross., p. 1045, t. xl. figs. 13, 14. 



t Remel^, Zeitschr. deut.geol. Gesell., Bel. xli., p. 762, t. xxx. 



I Barrande, op. cit., p. 81, pi. xi. figs. 14-25, pi. xv. figs. 34-36. 



