80 NEW PALEOZOIC VERTEBRATA. [Feb. 5, 



segmented. The remainder of the surface is marked by rather close 

 lines, which radiate from the reticulate center to the borders, and 

 which are rarely connected by cross lines. A coarse groove enters 

 proximad at one-third the width and extends across the scale 

 towards the long margin without reaching it. This reminds of the 

 groove in the S. j-eticulatus. 



Measuremefits. MM. 



Diameters of scale 3^^^ 



C longitudinal 57 



Five interradial spaces, transversely measured, in ... . 4 

 Nos. F. 47 and F. 48, Lacoe collection. 



The only species with which it is necessary to compare this one 

 is the S. reticidaius. The latter is without the radiating lines seen 

 in this species, and the scales are more contracted distally ; there 

 is also no distinct center. The size is less, but that may be indi- 

 vidual. 



Dedicated to Mr. R. D. Lacoe, to whom science is indebted for 

 the very fine collections he has made, and to the liberality with 

 which he has furnished them to students for research. 



Sagenodu^ quincunciatus, sp. nov. Rhizodus reticulatus New- 

 berry, Geol. Sur. of Illinois, iv, PL III, Figs. 13, 14. 

 PI. I, Fig. 6. 



Represented by six scales, two of them in mutual relation. 

 Size moderate; form wide, one extremity broadly truncate, the 

 other narrowed oval. No concentric lines (an exception noted 

 later) crossing the very fine radii. Reticulation coarse, quincun- 

 cial, areas diamond-shaped, the radial septa only continuing to the 

 truncate or distal margin ; the areas continued and becoming finer 

 to the proximal or narrowed margin. No distinct center, unless 

 the large tessellated area be considered as such. The areas are 

 coarser towards the long margins. There are some lines parallel 

 with the latter, which turn inwards parallel with the truncate border 

 and then cease. In one of the scales these lines continue inwards 

 50 far as to constitute parts of concentric lines. 



Measurements. mm. 



Diameters of scale \ 



( longitudinal 28 



Width of areas, from 5 to . 75 



