1815.] On the Ortlioceratites of Scotland. 801 



ia his History of Rutherglen and Helbrida, characterizes two 

 species of ortlioceratites as occurring in the Independent Coal 

 Formation of Lanarkshire. Martin, in his Petrifactions of Derby- 

 shire, mentions their occurrence in the lime-stones of that county : 

 and in the third volume of the Annals of Philosophy Dr. Thomson, 

 on the authority of Mr. Greenough, informs us that the orthoce- 

 ratite occurs in Ireland in rocks decidedly belonging to the floetz 

 formation. 



In addition to these notices of the occurrence of the orthoceratite 

 in the strata of this country, I have the satisfaction of stating to the 

 Society that ray cabinet of petrifactions contains ten species from 

 the rocks of Linlithgowshire. These are not all to be considered as 

 new species, and therefore interesting to the conchologist, as it is 

 probable that many of them have been described in the workg of 

 foreign mineralogists. But they may be regarded as of some 

 importance by the geologist, since they were all found by myself in 

 strata belonging to the Independent Coal Formation of Werner. 

 In order to elucidate this subject as much as possible, I shall give a 

 figure and description of the different species, that their existence 

 in other districts, or in other strata, may be ascertained by cora^ 

 parison. 



I.— SYSTEM.\TIC HISTOay. 



Ortiiocera. — Shell straight or slightly bent, subconical, formed 

 into chambers by simple transverse positions perforated by a tube. 



This genus may be conveniently divided into three families, dis- 

 tinguished by the external aspect of the shell. 



A. — Svrface of the Shell Smooth. 



The shells belonging to this family are regular in their form, and 

 the surface is smooth and even ; but when the shells are worn, and 

 the cKternal covering removed, they appear as if ribbed across, 

 owing to the partitions of the chambers becoming visible. 



1. 0. LcEvis. — Shell, conical; partitions, waved; chambers, 

 large; pipe, small and central. Plate XXXI. fig. 1. 



The length of the specimen which I possess is upwards of three 

 inchts. Its breadth at the base is nine-tenths, and at the apex two- 

 tenths, of an inch ; the shell is very thin ; the chambers arc about 

 two-tenths of an inch in depth ; the i)artitions arc waved on both 

 sides, and convex ; the pipe is central ; and in the middle of the 

 shell, where it is most apparent, it is about the fortieth of an inch 

 in diameter. 



The shell is now in the form of a yellowish-white soft lime-stone; 

 the inside is filled with granular lime-stone; but the pij)e contains 

 the same kind of limo-slonc in which tlie specimen is imbedded. 



This is proliably the shell referred to l)y I're in his History of 

 HuthcrgUn, p. TAir,, p|. xvi. (ig. 3, as the orthoceratites superficie 

 lavi. In some of tlic specimens which he found, the original shell 



