S. Allport — Un the Midland Basaltic Rocks. 159 



Om) Nami:3. Namks now AuorrEn. 



46. Cytheridcis unicornis, Jones. Cylhcridcin ? unicornis, Jonts. 



47. ,, tamariiidus, Jones. Loxoconcha tamnrinduK, Jones, sp. 



48. „ Colxvelletisis, Jonos. Cylhere ? Coliiellensis, Jones. 



49. „ Jiartonoisis, Jones. llynhateH liartoiiennit, Jones, sp. 



60. „ ^rtt;irfa, Miillcr, sp. Ci/f/irrc ho/c/lina, JonvH, {1670). 



61. ,, reii, Jones. Cyllicridcis ? ren, Jones. 



62. Bairdia subdeltoidea, Munster, sp. Maivdia J'uscaQ), Uiiidy : and B. tubtri- 



gonn, Bornemann. 



63. ,, coniractO; Jones. Bairdia contracta, Jones. 



64. Cytherella compressa, Miinstor, sp. Cyt/icriila compressa, Munster, sp. 

 64.* ,, ,. var. ncyricliii. „ Beyrichii, ]{f'uss, sp. 

 61'.** ,, „ var. intermedia. „ intermedia, Bornemann. 

 66. ,, Zondiniensis, Jones. „ Londinin^sis, Jones. 



66. „ Mucnsteri, Ea3mcr, sp. ,, Mucnsteri, Kromer, sp. ; and var. 



rectipunctata, Jones (1870). 



V. — On the Basaltic Eocks of the Midland Coal-fields. 

 By Samuel Allpokt, F.G.S. 



IN the Geological Magazine for March last, Vol. VI., p. 115, I 

 gave a short account of the discovery of Olivine and its pseudo- 

 morphs in the igneous rocks of the South Staffordshire Coal-field, 

 and as I have since then made a microscopical examination of 

 similar rocks from the surrounding district, I am induced to offer 

 the following ohservations. 



It has been long known that igneous rocks occur in the Coal- 

 fields of the Midland Counties ; they have been called " Basalts" and 

 " Greenstones" by the officers of the Geological Survey, but as no 

 account has hitherto been given of their mineralogical composition, 

 it has been uncertain whether they should be referred to the augitic 

 or hornblendic groups, or if they differed from each other in this re- 

 spect. On referring to the maps of the Survey it will be seen that 

 a continuous belt of Coal-measures extends for about 30 miles in a 

 northerly direction, from the Abberly Hills in the south, as far as 

 Lilleshall Hill, seven miles north-east of Wellington. 



The southern portion forms the Forest of Wyre Coal-field, and the 

 northern the Shropshire Coal-field. In the map containing the 

 former there is a mass of so-called "Greenstone" at Kinlet, and 

 another long band at Shatterford ; also a mass of " basalt" cappino- a 

 part of the Clee Hills. In the northern part of the district there are 

 shown several masses of " basalt" in the Carboniferous rocks, lying 

 between Wellington and Coalbrookdale. The mass marked " Green- 

 stone," forming the ridge of the Wrekin, together with the larger 

 mass to the north- west, belong to a totally different class of rocks. 

 The other localities from which I have collected specimens, are the 

 Whitwick Colliery, near Coalville, in Leicestershire, and the neigh- 

 bourhood of Matlock, in Derbyshire. 



A microscopical examination of thin sections, made from carefully 

 selected specimens, clearly shows that all the above rocks belong to 

 the same species ; they do not in fact differ more from each other 

 than different portions of any one of them, all being composed of the 



