290 



THE GEOLOGIST. 



the contrary, the two single Leptssnss, wliicli may, perhaps, be re- 

 garded as inhabitants of a somewhat deeper zone, both recm-. 

 Although, according to these lists, the Caradoc and Bala strata con- 

 tain six Discinse, four Lingulse, and one Trematis as true inhabitants 

 of shallow water, they are all different to the shallow- water inhabitants 

 of the Llandeilo beds, as also are the eight Annelida of the Llandeilo 

 different from the eight Annelida of the Caradoc and Bala beds. The 

 fauna of the littoral zone has been changed ; the few inhabitants of 

 deeper zones which have been found in the Llandeilo beds rise un- 

 changed in the following beds. I cannot think of speaking more on 

 British Brachiopoda to you. I have only thought these lines neces- 

 sary for the sake of showing you that the apparent mixture of both 

 groups in yom^ Silurian beds does not seem to me an argument 

 against my views ; and as I have now given you two examples in 

 which the shallow- water inhabitants were changed, the fauna of the 

 deeper zones remaining the same, viz., by the comparison of the 

 Utica slate with the Hudson risrer group, and of the Llandeilo with 

 Caradoc beds. I believe I must point out the very nice example of 

 the contrary given by your uppermost Silurian beds. Here you see 

 the sea getting gradually shallower, and out of about thirty species 

 of Brachiopoda known in the Ludlow beds, you only see a single one 

 rising up into the littoral or sub-littoral passage-beds, and occurring 

 there in great numbers, and that is lAngula cornea. Professor 

 Phillips has given a great number of data on these facts, and I 

 see from his paper on the Malvern s, that 'Bynch. nucula and Ghonetes 

 lata sometimes go a good way up, together with Biscina rugata, but 

 without continuing into the true passage-beds. 



ni. Bohemia. 



Mr. Barrande's Protozoic slates G, containing the first or primordial 

 fauna, have hitherto only yielded one JDiscina and one OrtMs as repre- 

 sentatives of our class. 



The second or lower Silurian fauna forms Mr. Barrande's etage D, 

 which is divided by this gentleman into five minor groups, viz. : — 



d 1, Slates at the base of the etage, near Komarow. 

 d 2, Quartzite of Mount Drabow. 

 d 3, Black, fohated slates. 

 d 4, Very micaceous slates. 

 d 5, Yellowish grey slates. 



The lower part of this etage is very poor in Brachiopoda, d alone 

 having yielded the genus OrtJiis. As to d 4 and d 3, M. BaiTande 

 has li;ul tlie extreme kindness to communicate to me the Hsts of the 

 Bracliiupoda known to him up to the present time from these beds. 

 I see from them that, making abstraction of several incomplete spe- 

 cimens, most of which, nccordino-to this distinguished paL^ontologist, 

 will prove to be Oiihldw, d 4 has o-iven thnte'en species, viz., two or 



