Yol. 52.] SILURIAN 8PECIE3 OF ACIDASPIS. 245 



any conclusions. So far, however, as the genus Acidaspis is con- 

 cerned, it appears that the British Silurian fauna is intermediate 

 between those of Sweden and Bohemia, but more closely allied to 

 the former. 



EXPLANATION OF PLATES VII. & VIII. 

 Plate VII. 



Figs. 1 & 2. Acidaspis crenata, Emm., sp. Wenlock Beds, Dudley. British 



Museum (Nat. Hist.). 1. Broad-taiied form, X 2. 2. Narrow-tailed 



form, X 2. 

 3 & 4. A. quinquespinosa, Salt. 3. Entire specimen, deprived of its test. 



Wenlock Limestone, Wren's Nest, Dudley. Brit. Mus. Nat. size. 



4. Head, with test preserved. Wenlock Limestone, Dudley. Fletcher 



Collection, Woodwardian Museum. X 2£. 

 Fig. 5. A. Brighti, Murch. Head. Wenlock Limestone, Dudley. Fletcher 



Coll., Woodw. Mus. X H. 



6. A. coronata, Salt. Wenlock Limestone, Dudley. Museum of Practical 



Geology, Jermyn Street, x 2. 



7. A. deflexa, sp. nov. Wenlock Shale, Dudley. Brit. Mus. X 2. 



Plate VIII. 



Figs. 1-3. Acidaspis Barrandei, Fletch. & Salt. Wenlock Limestone, Dudley. 

 Fletcher Coll., Woodw. Mus. 1. The most complete specimen known ; 

 anterior and posterior segments partially concealed. Nat. size. 

 2. Specimen showing internal view, with all the thoracic segments 

 displayed. Nat. size. 3. Head, showing occipital spines. X 1^. 

 4, 5. A. Hughesi, Salt. 4. Salter's type. Casterton Low Fell. Woodw. 

 Mus. X 2. 5. S. of Gale Garth, Casterton. Mus. Pract. Geol. X 2. 



Discussion. 



The President said that the Author was pursuing the only safe 

 method possible at the present day when working at any special 

 group, namely, to visit the Museums and localities abroad where 

 such specimens are to be studied. Mr. Lake had already visited 

 Sweden, and hoped to study the trilobites of Bohemia. His work 

 would be very welcome to all palaeontologists. 



Mr. Marr remarked that the Bohemian beds lying between the 

 Ordovician and Devonian were not very rich in trilobites, except 

 those of Upper Ludlow age. He asked whether Acidaspis erinaceus 

 was closely related to A. centrina, and whether the latter was 

 considered identical with A. granulata. He was glad to find that 

 A. Hughesi was at last described. Two entirely different species, 

 one Silurian and one Devonian, had been named A. Hughesi, with the 

 result that in future fossil lists A. Hughesi will probably be recorded 

 as a form passing from Silurian to Devonian. 



The Author replied that Acidaspis granulata, Ang., was gene- 

 rally looked upon by Swedish palaeontologists as a synonym of 

 A. centrina, Dalm. 



82 



