TRILOBITA. 



543 



many as twenty-two in number. Carmon is an Ordovician genus 

 allied to Proetus, but it has neither eyes nor facial sutures, and it 

 possesses eleven body-rings. The genus Harpides (apparently = 

 Erinnys of Salter) is an interesting type, which appears to be in- 

 termediate between the Proetidce and Ofeuidce, and which carries 

 back the range of the former into the Upper Cambrian. It has 

 the " limb " of the head-shield very wide, and covered with a net- 

 work of radiating and bifurcated nervures. On the other hand, 

 the Proetidce are represented in the Carboniferous rocks, not only 

 by Pi-oetus itself, but also by the genera Phillipsia, Griffithides, 

 and Brachymetopus, one species of the first of these genera having 

 been detected in deposits of Permian age. These types are there- 

 fore the most modern examples of the order Trilobita at present 



Fig. 405. — a, Griffithides globiceps, from the Carboniferous Limestone; b, Phillipsia DerH- 

 ensis, from the Carboniferous Limestone ; c, Glabella and free cheek of the same ; d, Hypostome 

 of the same ; E, Body-ring of the same. All the figures are enlarged. (After Henry Woodward.) 



known to us. In the genus Phillipsia (fig. 405, b-e) the body is 

 oval in form, and can be rolled up. The glabella (fig. 405, c) has 

 nearly parallel sides, with two or three lateral furrows, the hind- 

 most of which circumscribe a nearly circular basal lobe on each 

 side. There are only nine body-rings. The tail is semi-oval, dis- 

 tinctly segmented, and with an " entire " margin ; and the eyes are 

 large, reticulated, and reniform. Griffithides (fig. 405, a) resembles 

 Phillipsia in having nine body-rings, but the glabella is pyriform, 

 without lateral furrows, and with the basal lobes inflated, while 

 the eyes are small, lunate, and smooth. Brachymetopus, finally, 

 much resembles the preceding in form, but the glabella is small, 

 with lateral furrows but with no basal lobes. The eyes are small 

 and smooth, and no facial sutures are visible. The head-shield is 

 covered with a " small bead-like ornamentation " (Henry Wood- 



