V0I.51O MUECHIS0N1A AND ITS ALLIES. 223 



the plications are not so distinct as in larger and better preserved 

 individuals ; the characteristic moniliform sinual band is, however, 

 clearly marked. 



In the ' Faune du Calc. Carb. de la Belgique,' p. 15, De Koninck 

 states that M. Humboldtiana possesses a small umbilicus, and this 

 is represented in the figure of that work, but the figure in his 

 pre nous work ' Descr. des Anim. Foss. du Terr. Carb. de la Belgique,' 

 pi. xxxviii. fig. 1, shows the inner lip reflected on the columella 

 and covering the umbilical region, and this is the case with the 

 adult Belgian specimens in the British Museum (Natural History). 

 None of the British shells that I have seen show an open umbilicus, 

 but the aperture is not well preserved in any of them. That of the 

 type of M. fusiformis is the best, and there the columella appears 

 simple and the umbilicus is closed. 



The only Carboniferous species which this form resembles is 

 M. Vemeuiliana, De Kon., 1 which is like it in shape, but the band 

 is wider, and it is not moniliform, also the plications are absent. 

 Nevertheless it is sometimes difficult to tell to which species very 

 worn specimens should be referred. One of the shells in the 

 "Wbodwardian Museum described in a former paper 2 as M. Ver- 

 neuiliana is an example of this, for, as is there noticed, the keels 

 bounding the band are slightly undulating, and the band also is 

 rather narrower than is usually the case. There is no sign of the 

 plications, but the surface of the shell is much worn, which may 

 have caused their obliteration, and also on the other hand have 

 given rise to the undulating appearance of the sinual band. 



The type (PL VIII. fig. 9) is in the Gilbertson Collection in the 

 British Museum (Natural History). It consists of six whorls, and 

 the apex is broken. Length = 14 millim. ; width of body-whorl 

 = about 8 millim. 



Localities. The type is from Bolland. Other specimens occur at 

 Settle and Longnor, Staffordshire. From the former place there 

 are three examples in the "Wbodwardian Museum. The largest 

 (PI. VIII. fig. 12) has only three whorls preserved, the apex being 

 broken : its length is 16 millim. ; width =11| millim. Another 

 has part of five whorls whose length is 9 millim. The plications 

 are not so strong on this one. The York Museum also contains a 

 fine specimen from this locality (PI. VIII. fig. 11); there are five 

 whorls existing, of which the length is 20 millim., width 10| millim. 

 The largest shell is in the Museum of Practical Geology, from 

 Derbyshire ; it has the apex broken, leaving five whorls, whose 

 length is 26 millim. Besides this there are also two small shells 

 from Longnor in the same Museum, and another from the same 

 locality in the Museum of Science and Art, Dublin. 



Formation. Carboniferous Limestone (d 2 ). 



1 Ann. Mus. Boy. Hist. Nat. Belgique, ' Faune du Calc. Carb. de la Belgique,' 

 vol. viii. (1883) pt. iv. p. 25, pi. xxxiv. figs. 35-37. 



- ' Notes upon some Carb. Species of Murchisonia in our Public Museums,' 

 Quart. Journ. Geol. Soc. vol. xliii. (1887) p. 626, pi. xxiv. fig. 6. 



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