360 Annals of 'jhe Carnegie Museum. 



robust backward directed spine. The whole surface of the free cheek 

 is covered with small spines or pustules and between them are minute 

 pits. The eyes aie small, situated some distance from the glabella 

 and about opposite the anterior pair of glabellar furrows. 



Thorax. — The best specimens in the collection have only eleven 

 segments in the thorax, but all are small, and it is possible that larger 

 individuals would show more segments. Axis very convex, prominent, 

 occujiying more than one third of the width. Each segment bears, 

 on each side of the axis, near the dorsal furrows, a node with three 

 small spines, and along the top of the axial lobe are numerous small 

 spines. In removing the matrix from the specimen, the shell is almost 

 always broken from the axis of the thorax and only one specimen 

 shows any other than a smooth condition of the segments along the 

 axial lobe. 



The pleura are narrow and flat. The first segment ends in sharp 

 spines which are directed backward, but the succeeding ones seem to 

 be rather rounded on the ends and each bears three nearly horizontal 

 spines, two of them short and one very long. 



Along the front of each segment on the pleura is a narrow raised 

 border which becomes stronger toward the sides. (3n it are upward 

 pointing spines, and at the side of the pleuron it supports two small, 

 nearly horizontal spines. Back of this ridge is a narrow groove, 

 behind which is another ridge which bears numerous large spines 

 which point upward but ends in a large horizontal spine at the side 

 which points a little backward. 



Pygidium very small, semicircular; axis prominent, extending to 

 the posterior border. Margin entire, a narrow convex border orna- 

 mented with small spines running all around. The axis shows two or 

 three annulations, and behind the last annulation are rows of very 

 small spines which run over the axis parallel to the annulations. Side 

 lobes covered with small spines, and show two to four pairs of faint 

 ribs. 



Measurements. — A cranidium and six segments: length 19 mm.; 

 length cranidium 10 mm.; width 17 mm.; length of glabella 7 mm.; 

 width glabella 7 mm.; eye 5 mm. from posterior margin; 3 mm. 

 from glabella. Length of the large horizontal spine on 5th segment 

 4 mm.; spine from neck segment 3.5 mm.; a spine on middle of front 

 of cranidium 2.5 mm.; a spine on side of cranidium 3 mm. 



A Small Specimen. — One entire specimen is 4 mm. long and 2.25 



