/. JFopk'inson — On a new Silurian Annelide. 



77 



Old Names. 

 Baii-dia subdcUoklca, Muiistcr, sp. 



„ siliqua, Jonos. 



„ V(ir. a. 



„ Var. $. 



„ Hnrrisiana, Jones, 



,, flwi7«,v<ff, M iinster, sp. 



„ triqucira, Jones. 



„ siliciila, Jones. 

 Cytherella ovata, Roomer, sp. 



„ truncala, Bosquet. 



„ Williamsoniana, Jones. 



,, ? appei)diculata, Jones. 



,, .'' Mantelliaiia, Jones. 



„ ? Bosquetiana, Jones. 



Names now Adopted. 

 Bairdia suhdeltoidea, Muiistor, sp. 

 MncrocypriH siliqua, JimeH 

 Macroci/pris ? aicuala, Miinstcr, sp. ? 

 Tarucyprit} gracilis, Jones (1869). 

 Bairdia JIarrisiana, Jones. 

 Cytheridcis nttgusla, Miinster, sp. 

 Bairdia Iriqtcelra, Jones. 

 Bairdia silicula, Jniics. 

 Cytherella ovuta. Roomer, sp. 



„ Miien.ileri, Roomer, sp. 



,, Will iamsoniava, Jones. 

 Gytherura appcndiculata, Jones. 

 Cytherella Mantelliana, Jones. 

 Cythere Bosquetiana, Jones. 



VIII. — On Dexolites oracilis, a new Silurian Annelide, 



By John Hopkinson, F.G.S., F.R.M.S, 



(With a Woodcut.) 



OF the existence of Annelides during the Silurian period we are 

 ahnost as uncertain as of the existence of plants. Indeed, we 

 might reasonably doubt whether any Silurian fossils can with cer- 

 tainty be referred to this class. 



The tracks and filled-up burrows, formerly regarded as plants, are 

 as likely to be produced by crustaceans or molluscs as by worms :' 

 mere impressions or casts are almost equally micertain in their 

 nature, and the shelly tubes, such as Tentaculites and Cornulites, are 

 also of doubtful origin. ^ 



We have a remarkable instance of this uncertainty in the genera 

 ScoUtes and Arenicolites, which one of our most distinguished 

 palaeontologists has lately referred to as afibrding " more tangible 

 evidence of the Annelida " than such markings as Nereites Cam- 

 brensis, ^ but which, from the discovery of specimens showing 

 internal structure, are now known to be sponges,* 



It is therefore, with some doubt, that I describe as a new Silurian 

 Annelide, that, which, to say the least, appears to me as like a worm 

 as any Silurian fossil yet known. 



I assume my specimens to be impressions of the body of a worm, 

 and describe them provisionally as such, though it is possible they 

 may be only tracks. 



JDexolites, gen. noY. (St]^ — a worm; \ido<; — stone). Body slender, 

 cylindrical, flexible, tapering towards each end, and distinctly and 

 regularly annulated (See Woodcut), 



Dexolites gracilis, sp. nov. — Body from about half an inch to one 

 inch long, about one-twentieth broad, slightly tapering towards each 

 end, and with about thirty (or more) well marked body rings, which 



1 See " Siluria," 1867, p. 201 and p. 513.— Edit. 



2 Owen, Palaeontology, 1860, p. 40. 



3 W. H. Biiily, Charac. Brit. Foss., part I., p. xix. 

 * Nature, Dec. 30, 1869, p. 248. 



