Descriptions of New Species of' Fossils. 69 



Encrimjrus raricostatus n. sp. 



Pygidium subtriangular, convex ; length and breadth about equal ; anterior 

 lateral angles truncated so that the lateral margins commence opposite the 

 center of the pygidium ; axial lobe not very prominent ; crossed by about 

 sixteen smooth rings — the anchylosing of the posterior rings renders it diffi- 

 cult to determine the exact number. The lateral lobes are marked by six 

 broad, distinct, costse — the posterior pair unite back of the posterior termina- 

 tion of the axial lobe. 



Formation and localities. Trenton Limestone, Mineral Point, Beloit, and 

 north of Janesville, Wisconsin. 



ACIDASPIS, Murchison, 1839.. 



ACIDASPIS PARVULA, n. Sp. 



Body small, broadly elliptical, somewhat convex. Head semicircular in 

 outline, lateral angles terminating in slender spines. Glabella oblong ; owing 

 to the granulose character of the surface, and the slight glabellar furrows, the 

 lateral lobes and cheeks are scarcely denned. Eyes small, prominent. Thorax 

 strongly trilobate ; axial lobe two-thirds the width of the pleural ; segments 

 rounded on the axial lobe ; ea'ch one has four prominent tubercles upon the 

 upper surface, two each side of the center ; segments of the pleural lobes 

 consist of a posterior, rounded, elevated ridge, which has four strong tubercles 

 upon it, and a depressed anterior portion ; upon the free pleurae or spinous 

 extension of the elevated ridge of the pleural segment, two smaller tubercles 

 occur. 



Pygidium, too imperfect for description ; its strongly granulose surface, 

 and the prolongation of the lateral segments into long spines, are the only 

 characters clearly defined. 



Entire surface granulose, which, with the larger granules or tubercles upon 

 the head, the twelve rows of tubercles upon the thorax, and the continuation 

 of the central rows on the pygidium, gives this species a strikingly peculiar 

 appearance that distinguishes it from the associated Acidaspis Trentonensis, 

 and all described species of the genus. 



For)uatio?i and Locality. Trenton Limestone, Trenton Falls, N. Y. 



DALMANITES, Barrande, 1852. 

 Dalmanites intermedius, n. sp. 



G-eneral form narrow, ovate, moderately convex. Head subcrescentiform, 

 with a narrow margin, which is slightly produced in front of the glabella; 

 posterior lateral angles terminating in short spines. Frontal lobe of glabella 

 subrhombic, slightly convex ; anterior lobes subtrigonal, separated from the 

 frontal and middle lobes by well-defined glabellar furrows, which penetrate 

 from each side one-third the distance across the glabella ; middle lobes sub- 

 rectangular, shorter and smaller than the anterior lobes ; posterior pair as 

 rudimentary tubercles upon the anterior margin of the occipital furrow. 

 Occipital segment comparatively broad and elevated posteriorly above the 

 highest point of the glabella, narrowed toward the dorsal furrows, angular, and 

 abruptly turned downward, at the posterior margin. Occipital furrow regu- 

 larly concave, extending on the cheeks as a marginal furrow to the lateral rim. 

 Eyes prominent, palpebral lobe depressed, except at the outer margin, which 

 forms a rim around the top of the eye. 



Thorax tapers rapidly from about the center towards the pygidium ; axial 



