GLOSSARY 



Anterior Situated in front. 



Anterior limb of the facial suture That portion of the facial suture 

 lying in front of the eye. i 



Appendage A jointed process, two of which were borne by each seg- 

 ment of the trilobite body. 



Axial furrows Furrows or depressions bounding the axial or median 

 longitudinal lobe of the trilobites; same as dorsal furrows. 



Axis The median longitudinal lobe of the trilobites. 



Carapace The hard shell covering the -dorsal surface of the trilobite. 



Cephalon The head of trilobites 



Cheeks The two lateral portions of the head or cephalon of the trilo- 

 bites, divided into fixed and free cheeks by the facial suture. 



Compound eyes EyeS commonly present upon- the free cheeks of trilo- 

 bites; they are made up of a large number of smaller facets. 



Cranidium The portion of the head or cephalon of the trilobite lying 

 between the facial sutures, comprising the glabella and the fixed 

 cheeks. 



Distal Away from the center. 



Dorsal Pertaining to the back. 



Dorsal furrows The furrows or depressions bounding the axial or medial 

 longitudinal lobe of the trilobites; same as the axial furrows. 



Doublure The infolded margin of the trilobite test. 



Endopodite The inner of the two distal divisions of the typical crusta- 

 cean appendage. 



Exopodite The outer of the two distal divisions of the the typical crus- 

 tacean appendage. 



Eye lines A pair of raised lines reaching from the sides of the glabella 

 to the compound eyes or the ocelli of Some trilobites. 



Eye lobes Lobes of the x fixed cheeks within the inner margins of the 

 eyes. The palpebral lobes. 



Facial suture The suture in the head or cephalon of the trilobite separat- 

 ing the fixed from the free cheeks. 



Fixed cheek The portion of the cephalon or head of the trilobite lying 

 between the glabella and the facial suture. 



Free cheek Lateral portion of the cephalon or head of the trilobite, 

 lying beween the facial suture and the lateral cephalic border. 



Furrows Grooves or narrow depressions. 



Genal angles The postero-lateral angles of the cephalon or head of the 

 trilobites. * 



Genal spines The posterior prolongation into spines of the genal angles 

 of trilobites. 



Glabella The central or axial portion of the cephalon or head of trilo- 

 bites. 



Gnathobase The basal joint of the ventral cephalic appendages of 

 trilobites, modified to function as mouth parts. 



Holochroal eyes^Compound eyes of the trilobites whose visual area is 

 covered with a continuous horny integument. 



Hypostome The under lip of trilobites. 



