THE FAUNA OF THE ST. JOHN GKOUP. 77 



Localily. Twelve specimens, all collected by E. W. Ells, at Porter's Stream, N. B., in 

 ISTS. (Horizon. From Div. l.d.—Q. F. M.) 



PARADOXIDES, Brougii. 



I shall have occasion to describe three new forms which have been obtained since my 

 last paper was written. 



Paradoxides Acadicus, j>ar. Surtcus. (Plate VII. Fig. 16.) 



Head shield between the sutures narrow and long, with a large glabella. The length 

 is equal to the anterior transverse diameter, and is one ninth less than the width between 

 the ej^elobes. 



The anterior margin is regularly arched, and the fold is separated from the glabella 

 by a furrow connecting the two limbs of the flat area. 



The glabella is one quarter longer than wide ; it is regularly rounded in front and 

 the sides are nearly straight. The greatest width is little more than a quarter from the 

 anterior end. The furrows are deeply cut near the sides of the glabella, especially the 

 two first, which go entirely across, but are shallow in the middle third. The first furrow 

 connects by a flattened space on the top of the glabella with the occipital furrow ; both 

 the first and second furrows arch backward. The third and fourth furrows in some 

 examples are as distinctly impressed as the two first. . The third extends about one third 

 across, and the fourth more than one fourth across the glabella. 



The occii^ital ring is strongly arched backward from the posterior margin, and is 

 elevated posteriorly ; it has a well marked tubercle one third from the posterior margin ; 

 the furrow is deeply impressed in the outer quarter, but is quite shallow for the rest of 

 the way across. 



The posterior margin is strongly arched backward toward the extremity, where it is 

 triangularly pointed. The fold is narrow, but widens somewhat toward the end, and the 

 furrow is of nearly equal width throughout. 



The fixed cheek is bounded by a parabolic curve on the outer side, and is nearly 

 straight behind ; it slopes from the posterior inner angle to the front and to the posterior 

 outer angle. The eyelobe is continuous ; it is narrow and round, and is prominent at the 

 anterior and posterior extremities. 



Sculpture. The anterior marginal fold is traversed by parallel raised lines, from six to 

 nine in number, which anastomose at intervals ; the flat area has very fine granulations. 

 The glabella is covered with distinct granulations, and also has around the front of the 

 dome numerous short interrupted raised lines, coarser than those of P. Elemiiiicus, but finer 

 than the interrupted ridges found on the front of P. lameUatus. In young individuals, 

 these minute interrupted ridgiets cover the whole dome of the glabella as far back as the 

 third furrow, except on the slope behind the summit, where they are replaced by granula- 

 tions. 



This is a very marked variety of P. Amdkus and may proA^e to be a separate species. 

 The proportion of the glabella to the head shield between the sutures in P. Acadicus (type) 

 is 1 to 2J ; in this form, it is 1 to 2. In the variety the anterior transverse diameter 

 between the sutures is just equal to the length of the shield, in the type it is a sixth 



