3 NEW PROETIDE TRILOBITE LARVAE FROM THE LOWER ORDOVICIAN GARDEN-CITYFORMATION IN SOUTHERN IDAHO

Larvae of three proetide trilobites are described from the Garden City Formation: Proetide A, Goniophrys prima, and Licnocephala cavigladius . The larvae of Proetide A share a spindle-shaped axis and natant hypo stomal condition with other proetide larvae as synapomorphies. The for ward-tapering glabella and slender posterior fixigenal area of post-la rval cranidia of Proetide A indicate a close affinity to the earliest proetide family (Hystricuridae). The primitive nature of the larvae of Proetide A is further supported by the possession of plesiomorphic fe atures, including four glabellar lobes and bilobed axial lobes (L1/L2/ L3). Larval features of Goniophrys prima (a telephinid) such as an ell iptical outline and smooth exoskeleton are not consistent with the hyp othesis that the genus is the ancestor to younger telephinids. The lar vae of Licnocephala cavigladius are typical of the Bathyuridae in havi ng a smooth, ovoid shield and less distinct axial furrows.