CRUSTACEA. 31 



of short spinules upon the lateral margins. These spinules are five in number 

 upon each side, the first being the largest, their size diminishing posteriorly so 

 that the last is little more than a crenulation of the margin. They are short, 

 stout, acute, and directed backward. The terminal spine of the pygidium also 

 is relatively longer and more slender than in the normal form. 



This specimen is from the decomposed chert of the Corniferous limestone at 

 North Cayuga, Province of Ontario. 



DaLMANITKS (HaI SMAWIA) I'HACOl'TYX, 11. Sp. 

 PLATE XI \. FIGS. - 



Fragments of three large pygidia show pleura' which are broad on the anterior 

 margin, but narrow rapidly backward and are abruptly deflected toward the 

 posterior extremity. The margin is entire and the border quite narrow, 

 widening at the posterior extremity, where it is laterally flattened and pro- 

 duced into a stout spine, having about one-fourth the length of the pygidium, 

 and strongly bent upward. 



The axis is composed of eleven or twelve moderately broad annulations, 

 and towards its posterior extremity merges into the caudal ridge and spine. 



The pleural bear twelve or thirteen ribs which are separated by wide, shal- 

 low sulci, and are strongly curved backward near their distal extremities. 

 Each of these annulations is conspicuously sulcate. The surface is covered 

 with spinules and acute tubercles which appear to be irregularly scattered 

 over the annulations. On the axis they are sometimes in pairs or in single 

 transverse rows, becoming crow r ded together near its margins; on the pleurae 

 they appear to lie exclusively upon the anterior limb of each annulation, 

 although the larger spinules are often so broad at the base as to extend across 

 the entire width of the annulation. The surface between the tubercles and 

 spinules is covered with fine granulations. 



Dimensions. The largest and most complete specimen observed has a length 

 of 62 mm. to the tip of the caudal spine; its width across the anterior 

 margin, when entire, would be about 85 mm. 



Observations. This species, though imperfectly known, is of interest as pre- 

 senting a continuation into the Devonian formation, of a type of Dalmanites 



