BRITISH SILURIAN BRACHIOPODA. 75 



We have omitted from the Table the species that occur in the Upper Llandovery in 

 the County of Shropshire, as we have been unable to complete the list in time ; but will 

 refer to them in the sequel. Many most important works and papers relating to British 

 and foreign Silurian Brachiopoda have been published since the time I issued the last 

 portion of my ' Sihirian Monograph.' The most extensive and important of all of them 

 is that by Mr. Barrande on the ' Species that occur in the Silurian System of the centre of 

 Bohemia,' 153 plates being devoted by that eminent palaeontologist to their illustration 

 (vol. V, 1879). A small number of the Bohemian species occur also in Great Britain, 

 and will be referred to in the sequel. 



We must not omit to refer to the many important boring operations that have taken 

 place in England, and especially in the middle and southern portions of the kingdom, 

 during the last few years ; especially to that of Ware, in Hertfordshire, so well 

 described by Mr. R. Etheridge, at pp. 290 and 295 of the ' Popular Science Review ' 

 for July, 1879. In that valuable communication Mr. Etheridge intimates that the 

 Silurian floor of Wenlock age, dipping at an angle of 40°, was reached at the depth of 

 800 feet from the surface, and upon it rest the Cretaceous and Tertiary series of 

 Hertfordshire. All the Silurian fossils were obtained from a core less than three feet in 

 length and one foot in diameter. Mr. Etheridge enumerates thirty-three species belonging 

 to the Protozoa, Echinodermata, Annelida, Crustacea, Brachiopoda, Conchifera, Gastero- 

 poda, and Cephalopoda. 



The Brachiopoda, of which I have seen the series of specimens at the Museum of the 

 School of Mines in Jermyn Street, include: — 1. Orfhis elegantula, Dal.; 2. Whit- 

 fieldia tuviida,T>a[.; 3. Ci/rfia exporrecta,V^d\\\. ; 4. Spirifera jjlicatella, hm^. ; 5. Sp. 

 elevata, Dal.; 6. Athyris ; 7. PJwIidops {Crania) imjMcata, Sow.; 8. Bhynchonella 

 cuneata, Dal., or B. deflexa. Sow,; 9. Atrypa reticularis, Linn.; 10. Pentamerus 

 yaleatus, Dal.; 11. P. lingiiifer. Sow.; 12. Strophomena euylypha, Dal.; 13. St. 

 rIiomboidalis,^\\ckeia%. ; 14. St. antiquata,So'w. ; 15. Leptcena transversalis,T>si\. ; and 

 16. Chonetes, sp. Mr. Etheridge quotes likewise Stroph. reticulata, M'Coy, and Leptcena 

 sericea. Sow., but I do not feel certain that the two last-named identifications are quite 

 correct. 



In his 'Thesaurus Siluricus,' published in 1868, Dr. Bigsby enumerated some 1650 

 species of Silurian and Cambrian Brachiopoda. Since then a large number have been 

 added by Barrande and many European and American palaeontologists, so that if we 

 put the number of named species at 1800 we would not exceed the estimate. A very 

 large reduction in that number would, however, have to be allowed for synonyms ; 

 and indeed, it would not be possible in the present state of our knowledge to correctly 

 estimate the number of really good species hitherto discovered. 



