63 



trilobites are not Confined , to a geological period 

 more remote than That which has produced the ani- 

 mals with oculiferous tubercles. 



GENUS OGYGIA. Brongniart. 



In the vast quarries of slate at Angers, in France, 

 there is frequently noticed two very remarkable or- 

 ganic remains, which have for a loic^ time excited the 

 attention of naturalists. To receive these curious 

 relics, Professor Brongniart established the genus, 

 Ogygia, which he thus characterizes. Body much 

 depressed elongated into an ellipse, terminated in 

 points nearly equal at its extremities, and not capa- 

 ble of contracting itself into a spherical form. The 

 buckler is bordered by a slight longitudinal furrow, 

 rising from its anterior extremity, and its posterior 

 angles terminating in elongated points. The abdo- 

 men has eight articulations, and its longitudinal lobes 

 are not very prominent. The eyes are neither promi- 

 nent nor reticulated and there are no other protube- 

 rances on the buckler. 



In Professor Brongniart's original work on theTri- 

 lobites, he has described the two specimens from 

 Angers, under the specific names of Guettardi, and 

 Desmarestii, in compliment to M. M. Guettard and 

 Desmarest; and in De La Beche's Manual of Geolo- 

 gy, we are informed that he has since identified two 

 other species; one of which is supposed to be found 

 in North America; this he calls Ogygia Sillimani; 

 the banks of the Mohawk River, near Schenectady, 



