October, 1913. New Trilobites — Slocom 45 



Cephalon: The head of a trilobite. (C) 



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

 bite, divided into fixed (7) and free (5) cheeks by a facial suture. 



Compound eyes: Eyes commonly present upon the free cheeks of 

 trilobites; they are made up of a large number of small facets. (4) 



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

 between the facial sutures, comprising the glabella and the fixed cheeks. 



Distal: Away from the median line. 



Dorsal: Pertaining to the back. 



Dorsal furrows: The furrows or depressions bounding the axial or 

 medial longitudinal lobe of a trilobite; same as the axial furrows, (d) 



Doublure: The infolded margin of the trilobite test. 



Facial suture: The suture in the head or cephalon of a trilobite 

 separating the fixed from the free cheeks. (2, 6) 



Fixed cheek:- The portion of the cephalon or head of a trilobite 

 lying between the glabella and the facial suture. (7) 



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

 lying between the facial suture and the lateral cephalic border. (5) 



Frontal lobe: That portion of the glabella anterior to the first lateral 

 furrows. (19) 



Genai angles: The postero-lateral angles of the cephalon or head of 

 a trilobite. 



Genal spines: The posterior prolongation into spines of the genal 

 angles of a trilobite. (9) 



Glabella: The central or axial portion of the cephalon or head of a 

 trilobite. (g) 



Holochroal eyes: Compound eyes of a trilobite whose visual area is 

 covered with a continuous horny integument. 



Hypostoma: The under lip of a trilobite. 



Lateral furrows: The transverse furrows or grooves of the trilobite 

 glabella, sometimes continuous across the glabella and sometimes 

 greatly modified. (1) These furrows define the lobes of the glabella. 



(i7) ' 



Marginal border: The thickened or otherwise differentiated external 

 border of the cephalon and pygidium of a trilobite. (15) 



Marginal furrow: The groove or depression lying just within the 

 marginal border of the cephalon and pygidium of a trilobite. (8) 



Occipital furrow: The posterior transverse groove or furrow of the 

 glabella of a trilobite, lying in front of the occipital segment. (16) 



Occipital lobes: Small, lateral lobes of the occipital segment present 

 in some trilobites, which are morphologically different from the lateral 

 lobe of the glabella. « 



