46 ORDOVICIAN AND SILURIAN BELLEROPHONTACEA. 



3. Conradella ? multilineata, sp. nov. Plate IX, figs. 3, 4. 



Specific Character,^. — Shell discoidal, composed of 3 — 4 wliorls ; umbilicus large, 

 fully half the diameter of the shell ; wliorls slightly overlapping, very slowly 

 increasing in size, subtriangular in cross-section. Outer whorl with sides somewhat 

 inflated at base ; dorsum compressed, subangular, bearing high keel [and slit- 

 band ?] ; umbilical edge subangular ; umbilical slope steep. Surface ornamented 

 with numerous regular closely-placed, equidistant fine thread-like transverse lines, 

 minutely fimbriated, scarcely arched, meeting keel at about 75°. 



Dimensions. — Average height about 12 mm. 



Horizon. — Middle Ordovician : Whitehouse Group. 



Locality. — Shalloch Mill, near Girvan. 



Remarks. — None of the available specimens are well preserved, and it is 

 doubtful if a slit-baud is present, but it appears probable that this species should 

 be referred to the genus Conradella rather than to Cyrtolifes, for it much resembles 

 G. girvanensis from the same horizon and locality, differing chiefly in the 

 ornamentation. All the examples are in Mrs. Gray's Collection. 



4. Conradella fimbriata, Ulrich and Scofield. Plate IX, fig. 5. 



1897. Conradella fimhriaf a, Ulrich and Scofield, Final Rep. Geol. Nat. Hist. Surv. Minnesota, vol. iii, 

 pt. 2, p. 907, pi. Ixii, fig. 66, pi. Ixvii, figs. 7—10. 



Specific Characters. — " Shell discoid, from 18 mm. to 25 mm. in diameter. 

 Volutions about three, enlarging more rapidly than usual for the genus, very 

 strongly and rather abruptly carinate, broadly subcordate in section, wider than 

 high, narrowly rounded in the lower part of the sides ; umbilicus comparatively 

 small, equalling two-fifths of the diameter of the shell ; slit extending uearly half 

 a volution posterior to the apertural margin. Aperture abruptly expanded at 

 frequent intervals, the expansion left behind forming transverse, imbricating 

 folded lamellge, the anterior edges of which are strongly serrated and project, 

 collar-like, 3 or 4 mm. forward and outward from the surface of the last volution. 

 Each expansion has seven folds, the lower one faint, the upper one strong. Occa- 

 sionally a smaller one is developed between each pair of the latter. The entire 

 surface is covered^ with very fine longitudinal and transverse lines. All the 

 transverse markings cross the volutions obliquely. When, as is generally the case, 

 the projecting lamellae are broken away the surface presents two or three more or 

 less obscure revolving ribs on each side of the prominent keel " (Ulrich and 

 Scofield). 



Horizon. — Upper Ordovician : Drummuck Group (Starfish Bed). 



