480 ANNELIDA. 



of these minute fossils, and owing to the isolated condition in which 

 they occur, it is difficult to refer them to genera and species. Most 

 of the fossil forms resemble the jaws of the living family of the 

 Eunicea, and such have been referred to the genera Eunicites (fig. 

 345, a), Arabellites (fig. 345, b), Lumbriconereites, &c. Others 

 correspond with the recent genus Glycera, and have been placed 

 under Glycerites (fig. 345, c) ; while Nereidavus appears to represent 

 the existing family of the Lycoridea. 



As regards their distribution in time, Hinde has shown that these 

 fossil jaws are abundant in some parts of the Ordovician, Silurian, 

 Devonian, and Carboniferous formations ; and they are also known 

 to exist in Mesozoic and Tertiary deposits in actual connection 



A 



Fig. 345. — Jaws of Annelides from the Ordovician rocks (Cincinnati group) of North America. 

 A, Jaw of. Eunicites varians, enlarged 3% times; b, Jaw of Arabellites cornutus, enlarged 

 twelve times; c, Jaw of Glycerites sulcatus, enlarged fifteen times. (After Hinde.) 



with the bodies of their original possessors. If Rohon and Zittel 

 should prove to be correct in their view that the so-called " Cono- 

 donts " are really of the nature of the jaws of Annelides, then these 

 minute fossils occur in rocks as ancient as the Upper Cambrian ; 

 but the nature of these problematical bodies will be dealt with 

 more fully later on. 



Apart from the above-mentioned indubitable remains of Errant 

 Annelides, numerous more or less distinct worm-like markings, 

 which are found in muddy and sandy sediments throughout almost 

 the whole of the series of stratified rocks, have been referred to ani- 

 mals of this group. Some of these (such as Nereites and Phyllo- 

 docites) have been described as being of the nature of the petrified 

 bodies of Sea-worms ; but as they exhibit absolutely no structure, 

 it is in the highest degree improbable that this explanation of their 

 origin is correct. The true nature, in fact, of most of the remains 

 here in question must be regarded as exceedingly uncertain. Some 

 are, probably, really referable to the vegetable kingdom ; others are 

 almost certainly formed by Molluscs, or by Crustaceans ; others 

 are of entirely dubious affinities ; while others are, doubtless, really 

 due to the operation of Errant Annelides. It may be added that 

 the fossil remains which have been referred to Nemertean Worms 

 cannot at present be separated, in any satisfactory manner, from 

 those formed by Errant Annelides. Thus the so-called Nemertites 



