SPECIES OE MTTRCHTSON1A. 



625 



d'Arch. &de Yern. ('Geol. Trans.' 2nd ser. vol. ii. p. 356, pi. xxxii. 

 fig. 6), which is, I think, distinct, the whorls being much more exca- 

 vated, and in the type the band is grooved on all the whorls, while 

 on the variety a it is mnch narrower. 



There are about twenty-two specimens of this shell in the Wood- 

 wardian Museum ; the largest is one figured by M'Coy (pi. 3 h. fig. 11). 

 Its length is 58 millim., width of penultimate whorl 27 millim., 

 height 12 millim. The shell is imbedded in the matrix; it consists 

 of seven whorls, and the apex is broken. The base is rounded, and 

 the angle shows but slightly on the upper whorls, just above the 

 sutures. 



A smaller specimen in this museum has the angle well marked on 

 all the whorls. Only five whorls of it are preserved. A nearly per- 

 fect specimen consists of eleven whorls, and would, probably, have 

 one or two more if the apex were entire ; it is 45 millim. in length, 

 but the surface is badly preserved. None of these specimens have 

 the band much hollowed out in the centre on the upper whorls, it 

 being more or less solid on all the whorls. 



The specimen (PI. XXIV. fig. 5) in the Gilbertson Collection, figured 

 by Prof. Phillips (' Geol. Torks.' vol. ii. pi. xvi. fig. 16, sinistra) is 

 merely a cast consisting of two whorls, but it shows the strongly 

 marked characteristics of this species. The band is broad and flat, 

 and the slit in the outer lip is shown. 



There are four specimens in Prof. Phillips's collection in the 

 Oxford Museum, but none of them are well preserved. One, which 

 is much imbedded in the matrix, consists of about seventeen whorls, 

 and it has the strong angle below the band. 



Its length is about 36 millim. 



There are specimens of this shell in the Geological Society's Museum, 

 the Museum of Practical Geology, and the Kendal Museum; and there 

 are also one or two others in the Natural History Museum, besides 

 that figured by Phillips. 



Locality. All the above-mentioned fossils are from Kendal, with 

 the exception of the specimen figured by Phillips, which is from 

 Bolland. 



Formation. Mountain Limestone. 



Mr. Morton, Liverpool, has specimens in his collection from 

 Porth-y-Yaen, near Oswestry, Llangollen, and Mold. He divides 

 the Carboniferous Limestone of that district into the following 

 lithological divisions, in descending order : — Upper Black Lime- 

 stone, Upper Grey Limestone, Upper White Limestone, Lower 

 "White Limestone, Lower Brown Limestone. He finds that M. 

 heyidalensis, M'Coy, ranges throughout the series with the exception 

 of the Upper Black Limestone. It occurs in the Lower Brown and 

 Upper Grey at Llangollen, in the Upper White near Oswestry, and 

 in the Upper Grey near Mold. 



In the Wood Collection in the York Museum there is also a 

 specimen from Oswestry (PL XXIY. fig. 4). It consists of about eight 

 whorls, and the apex is broken. The band on the lower whorls is 

 solid, but on the upper it is grooved and composed of two keels. 



