SPECTES OE MTTKCHISONIA. 



629 



Length of the more perfect specimen 8 millim., width 5| millim. 

 Length of the cast 10 millim. These two shells are in the Carr 

 Collection in the Museum of Practical Geology. 



This species bears some resemblance to M. SedgwicJciana, de Kon., 

 but it is more elongated, the bands and grooves are not so evenly 

 disposed, and it is also much smaller. From M. suhsulcata, de 

 Kon., it is distinguished by the greater number of grooves possessed 

 by that species. The American form, M. terebriformis, Hall, 

 most nearly approaches it ; but it is ornamented with elevated spiral 

 striae below the band instead of with flat bands. 



Locality. Narrowdale. 



Formation. Mountain Limestone. 



MlJECHISONIA SPH-ZEEUL ATA , Sp. nOV. (PI. XXIY. fig. 10.) 



Shell elongated, conical, composed of numerous convex whorls. 

 The whorls are rendered slightly angular in the middle by the sinual 

 band. The band is broad and flat, and bounded by two narrow 

 grooves ; there is a wider and shallower groove in the centre of it. 

 Below the band there are five or six spiral lines ; they are some- 

 what indistinct, and are slightly reticulated with the lines of 

 growth. The lines of growth are strong, and curve backwards to 

 the band above, and forwards below ; the}^ are arched on the 

 band. The upper part of the whorl is smooth. The mouth is 

 longer than wide. 



There is but one specimen of this species in the Museum of 

 Practical Geology, and it has only four whorls preserved. 



Length 17 millim., width of body-whorl 8 millim., width of 

 penultimate whorl 7 millim. 



This shell is more elongated than M. zonata, and it is orna- 

 mented with fine spiral lines instead of with flat bands. It is 

 larger than M. terebriformis, Hall, the whorls increase more slowly, 

 and the lines below the band are very fine and more numerous, 

 instead of being raised spiral threads. 



Locality. James's Cleugh, King Water, Cumberland. 



Formation. Lower Carboniferous. 



MUECHISONIA TENTJISSIMA, Sp. nOV. (PI. XXIY. fig. 11.) 



Shell very elongated, turriculated. A perfect specimen would 

 possess from ten to twelve whorls. Whorls angular, and each 

 ornamented with six spiral keels. Three of these keels are placed 

 rather close together about the middle of the whorl and form the 

 sinual band ; the central keel is a little finer than the others. 

 Above the band a fine keel lies just below the suture, and below 

 the band there are two keels, the lowest of which appears just 

 above the suture on the upper whorls. On the body-whorl there is 

 also a very fine thread between the band and the uppermost keel. 

 The lines of growth are strong and very distinct ; they curve back to 

 the band above, and forward below ; they are arched on the band. 

 The specimen is imbedded in the matrix, and the body-whorl is 

 broken away from the rest of the shell. 



