Vol. 51.] MTTRCHISONIA AND ITS ALLIES. 229 



M. compacta, 1 Don., is the species which this most resembles, but 

 M. convpacta has more convex whorls, less deep sutures, the additional 

 keels on the body-whorl are absent, the apex is more obtuse, and the 

 nucleus is much more flatly coiled. None of the individuals that I 

 have seen show an open umbilicus, and it is open in some of the 

 young specimens of M. compacta. Length of specimen (PI. IX. fig. 6) 

 =5g millim. ; width = 3 millim. Length of specimen (PI. IX. fig. 7) 

 =4^ millim. ; width about 2 millim. Length of specimen (PI. IX. 

 fig. 11)=4| millim. ; width about 1| millim. 



Locality. Law, Dairy. Mr. Young also possesses examples from 

 this locality, as well as from Crawfield, Beith. 



Formation. Lower Limestone Series (cZ 3 ). 



Section Glyphodeta. 



Mtjrchisonia (Glyphodeta) eimbricarxnata, Young & Armstrong. 

 (PL IX. fig. 9.) 



Murchisonia fimbricarinata, J. Young & J. Armstrong, 1874, Trans. G-eol. 

 Soc. Glasgow, vol. iv. p. 279 ; J. Armstrong, J. Young. & D. Robertson, 1876, 

 Cat. West. Scot. Geol. Poss. p. 56 ; J. J. Bigsby, 1878, ' Thes. Dev.-Carb.' 

 p. 325 ; P. Etheridge, 1888, ' Foss. of Brit. Islands,' vol. i. Palaeozoic, p. 301. 



Shell small, conical, composed of more than seven whorls. Whorls 

 rounded, very slightly angular about the middle. Sinual band 

 situated on the widest part, broad and flatfish, with a fine linear 

 groove on each side. Ornamentation above the sinual band con- 

 sisting of two or three fine lines ; below, of two somewhat rounded 

 bands, with an additional band on the body-whorl. Both the lines 

 and bands are separated by grooves, those between the bands being 

 the deepest. Lines of growth distinct, causing the spiral lines and 

 bands to be almost beaded where they cross ; on the sinual band 

 they form strong raised crescents. Sutures deep, rather oblique. 

 Mouth unknown. 



The only species which this resembles is M. sonata, 2 Don., from 

 which it may be distinguished by its greater spiral angle, less con- 

 vex whorls, more prominent sinual band ornamented with raised 

 crescents, and by its beaded lines and bands. 



The single known specimen of this species is in the collection of 

 Dr. John Young, Glasgow. 



Length =7 millim. ; width of body-whorl = 3^ millim. 



Locality. Robroyston. 



Formation. Upper Limestone Series (d 3 ). 



Murchisonia (Glyphodeta) tjeniata, Phill. (PI. X. fig. 5.) 



Turritetta tceniata, J. Phillips, 1836, ' Geol. Yorks.' pt. ii. p. 229, pi- xvi. 

 fig. 7 ; T. Brown, 1849, ' Ulustr. Foss. Conchol. Great Britain & Ireland,' p. 71, 

 pi. xxxviii. fig. 7. 



1 ' Descr. of some New Sp. of Carb. Gasteropoda,' Quart. Journ. Geol. Soc. 

 vol. xlv. (1889) p. 624, pi. xx. figs. 9-13. 



2 ' Notes upon some Carb. Sp. of Murchisonia in our Public Museums,' 

 Quart. Journ. Geol. Soc. vol. xliii. (1887) p. 628, figs. 1-2. 



