BIHANG TILL K. SV. VET.-AKAD. HANM)L. BAND. 7. X:0 O. 9 



are discovered, showing the constitiient plates of the jaw- 

 armature in their relative positions, whicli, jndging from my 

 OAvn experience, seems at present unlikely, we shall have 

 to be content with a description of these detached jaw plates 

 based upon their nearest resemblances to tbose of existing 

 forms. The references to the genera will have to be regard- 

 ed as merely provisional, until further discoveries allow a 

 more correct classification to be adopted. Notwithstanding 

 this hindrance to a satisfactory arrangement, the number and 

 variety of these fossil jaws plainly indicate that this family 

 of Aunelids had attained to as great a development in the 

 Silurian period, as in the present time, and although their 

 remains have been so rarely discovered in the periods inter- 

 vening between the Silurian and the present, the rescmblance 

 of these microscopic fossils to the chitinous jaws of recent 

 forms is sufficiently clear to establish a genetic relationship 

 between them. 



Annelida Polychaeta. 

 Genns EUNICITES, Ehlers. 



Euuicites simplex, Hinde. Pl. I f. 1 — 4. 



1879. Eunicites simplex, Hinde. Quart. Jour. Geol. Soc. Vol. 35 p. 

 376. Pl. 19 f. 2. 



These jaws have the form of simple elongated hooks, with 

 rounded or obtuse basal ends, they gradually curve forwards 

 and the extremities are blunted. There is a larsre, somewhat 

 oval aperture at the proximal end for the insertion of the 

 muscle; the jaw appears to be hollow quite to the point. In 

 size these jaws vary between 0,r>i and 1,44 mm. in length, 

 and 0,1 and 0,3 mm. in Avidth. Examples similar to these 

 are present in the Canadian Silurian and the Carboniferous of 

 Scotland. In general form these jaws approach closest to the 

 pincers (Zange) of the existing genns Eunice; but they differ 

 therefrom in the absence of an articnlatino- surface at the 

 proximal end, by which the pincers in the existing forms are 

 conuected with the supports. The specimens are not uncom- 

 mon. I have only found them in material from Wisby. 



Eunicites, sp. Pl. 1 fig. 5. 



Small compressed spatula shaped bodies with rounded, 

 somewhat inflated front margins, the proximal end hollow. 



