84 PROCEEDINGS OF THE 



in their characters than the armature of the carapace or rostrum. 

 Any deviation detected from the normal form in the caudal 

 appendages of these animals is always a good reason for further 

 scrutiny of all their parts. 



Mr Robertson at same time exliibited a specimen of Terehellides 

 strcemii — an annelid new to the British fauna, also from the Firth 

 of Clyde, where it is by no means rare. He had first dredged it, 

 when in company \n.i\\ Mr Keddie, in the Kyles of Bute, in the 

 summer of 1862, and found it last summer in Lochlong, Lochgoil, 

 and off Cumbrae — ^the habitat in each case being a dark-coloured 

 mud. Mr Eobertson likewise gave a description of its habits, as 

 observed by himself. 



PAPER READ. 



On the Fossil Shells, Anthracosia, Anthracomya, and Anthracoptera, 

 found in the Lanarkshire Coalfield. By Mr John Young. 



Specimens from his collection, belonging to various species of 

 these genera, were exliibited; also specimens of the rock known as 

 the Cambuslang marble, at one time worked in this district for 

 ornamental purposes, and which is principally made up of shells 

 belonging to this family, showing that they must have swarmed over 

 certain tracts during the coal period, as thickly as the Mijtilidce- in 

 our present seas. He stated that for many years these shells were 

 regarded as nearly allied to the Unios, or fresli-Avater mussels 

 of our present lakes and rivers, and that they were thought to 

 indicate a fresh-water origin for the various coal strata in which 

 they are found. But the investigations of the last few years have 

 shown that they differ in several of their characters from true 

 Unios; and, from the finding of marine shells associated with them 

 in various districts, the strata in which they are found is now 

 regarded as not so exclusively of fresh-water formation as was once 

 supposed. He further stated that geologists had much to learn 

 regarding the life of the coal period, before they could state 

 definitely whether the beds in which these shells occur are truly of 

 marine or fresh water origin. He, however, hoped that the day 

 was not far distant when a more complete knowledge would be 

 obtained of the varied conditions under which many of the beds 

 connected with our coal strata were deposited — a result which 

 could only be satisfactorily accomplished by a more careful study 

 of the animals and plants found in these strata. 



