334 SYSTEMATIC PALEONTOLOGY 



four rows of deep, rounded pores or punctures; the rows increase by im- 

 plantation as they approach the posterior lateral margins, where they 

 number from six to seven. 



" The thorax consists of six articulations ; axial lobe depressed, convex, 

 narrow, and carrying on each side between the segments two rows of 

 minute punctures ; lateral lobes flat, and three times as wide as the central 

 lobe ; pleura straight, and furrowed on the outer half. 



" Pygidium small, acutely semi -elliptic, being about four times as wide 

 as long, and broadly rounded in outline behind, with a raised and thick- 

 ened margin ; axial lobe very small, and composed of four obscurely defined 

 segments; lateral lobes each with three segments. 



" Length of largest known specimen, 6 mm. ; length of cephalic shield, 

 3.5 mm. ; breadth of do., 7 mm. ; length of thorax, 1.25 mm. ; breadth of 

 do., 4.5 mm.; length of pygidium, 75 mm.; breadth of do., 4 mm." 

 Ulrich, 1878. 



This interesting species is distinguished from all American and Euro- 

 pean species of the genus in the straightness or slight concavity of the 

 posterior edge of the cephalon, and in the relative flatness of the border. 

 The thorax also is shorter and the neck spine longer. In young specimens 

 such as the original type, these peculiarities are especially marked. In 

 old examples the posterior edge of the cephalon turns somewhat pos- 

 teriorly at the ends, but it is still much less curved than in all other species. 



Occurrence. MARTINSBUEG SHALE (Eden division). Jordans Knob, 

 one and one-half miles northeast of Fort Loudon, Cowans Gap, five miles 

 northeast of McConnellsburg, and Tuscarora Mountain, two and one-half 

 miles southeast of McConnellsburg, Pennsylvania. Eden shale at Cov- 

 ington, Kentucky. 



Collection. TJ. S. National Museum. 



CRYPTOLITHUS EECURVUS Ulrich n. sp. 

 Plate LVI, Figs. 14-17 



Description. This new species has been discriminated by E. 0. Ulrich, 

 who has had the opportunity of studying a large number of foreign and 

 American specimens of this genus. Cryptolithus recurvus differs from 



