[ 71 ] 



were subsequently very generaUy adopted both by British and 

 foreign palaeontologists, but be did not omit to impress upon bis 

 readers tbat we were not then, nor were we even yet, quite in a 

 condition to prepare a really complete, permanent, or wholly 

 satisfactory classification of the numerous species composing tbe 

 class. In 1853, be divided tbe Bracbiopoda into eight families, 

 comprising twenty-four genera and twenty-two sub-genera, but 

 during tbe years tbat bad elapsed since 1853 up to the present time 

 some seventy-two more genera or sub-genera bad been proposed, 

 and of which he published a list in the Stwsea; PaiZj/ A^etus newspaper 

 for the 20tb of August. 1872. Much consideration on bis part had 

 been devoted to tbe subject, but be felt that in order to place tbe 

 known genera and species into their respective families, or into new 

 ones that would have to be created, much more information would 

 have to be acquired. Tbe subject was immense, when one had to 

 grapple with between five and six thousand described species, 

 varieties, or synonyms. J. Bigsby gave :i list of upwards of three 

 thousand species alone from the palceozoic rocks, and it must likewise 

 be borne in mind that many of tbe extinct genera had as yet been 

 but imperfectly elaborated. Tbe material in band was, however, so 

 great tbat, with time, paleontologists would be able to lay before 

 tbe public a complete history of a class, which, as would be shortly 

 shown, bad played an important part in the great life-system of 

 our globe, from its dawn to tbe present time. It would be necessaiy 

 though, to admit the two great divisions Tretenterata and 

 Clistenterata into any scheme of classification, although it was 

 impossible to say whether or not all the extinct genera were 

 provided or otherwise with an anal aperture. Tbe Tretenterata 

 comprised the families LinguUdce, Discinidce, Craniadce, and (?) 

 Trimerellidoe. Each of these families was composed of several 

 genera. The Clistenterata would include tbe families Terehratulidce, 

 Bhycnchonellidce, Spiriferidce, Strophomenidce and Productidce. By 

 far the larger number of described genera and species would have to 

 be located in this great division of the Bracbiopoda. 



DISTRIBUTION IN TIME. 



Assuming that they were all acquainted with tbe geological 

 divisions into which tbe crust of this earth had been grouped, he 

 might at once observe that, as was justly remarked by Barrande, 



