Help with identify trilobite

[Tomek]

Hi,

I'm geologist from Poland, and I found trilobite fossil at work.

 

Pygidium length and width are about 1,5 cm. It is from glacial aggregate; from Sweden (maybe Gotland). Fossil is from Cambrian - Silurian limenstones (perhaps Ordovician).

 

I can't identify this kind of trilobite.

Pygidium is little different. Pleura furrow is double in half or less length. The right pleura is further in limestone, and is longer 2-3 mm. Last axial ring seems like connect with upper axial ring.

 

Thanks for any help and suggestions.

 

Right pleura:

[Fossildude19]

Looks like some sort of Calymenid.

 

@Kane  @piranha

[piranha]

There are numerous Silurian calymenids from Gotland and one in particular that exhibits the distinctive posteromedial pleural ribs that run adjacent to the axial furrow. Unfortunately, the proposed subspecies of Calymene tentaculata campana  from the PhD thesis of Siveter 1973 is a name that is not formally published and therefore unavailable: nomen nudum. In the meantime and pending any future description you can label it: Calymene cf. tentaculata

 

Siveter, D.J. 1973
Trilobites of the Family Calymenidae from the Ordovician, Silurian and Devonian Systems of North-West Europe.
PhD Thesis, University of Leicester, 380 pp. 92 plts.  PDF LINK

[Tomek]

Thanks a lot ! 

It looks like pleural ribs can be also longer, and maybe preservation of this pleura is disfficult. I will prepare this fossil better for more accurate description.