THE FAUNA OF THE ST. JOHN GEOUP. 73 



elevated lengthwise, having an elongated tubercle at the axial line ; tlie third segment oi' 

 the axial lobe is narrow like the first, and the fourth is snbtriangular. 



Sculpture. The surface of the test in this species has a velvety appearance, and under 

 the lens is seen to be covered with minute granulations, the surface also is rugulose or 

 uneven, and the test thin and more apt to be distorted than those of the two preceding 

 species. 



The parts of the body in this and the succeeding species are more frequently found 

 connected, than are those of the preceding species ; and while the species above described 

 are usually found doubled together, this and the following species are frequently spread 

 out at length. This species resembles A. scarabeoides of the Welsh Cambrian rocks, but has 

 a narrower glabella with a more obtuse front. 



Length, 11 mm. Width, 6 mm. 



Horizon and Locality. In the fine dark grey shales of Div. l.d, at Porter's Brook, St. 

 Martin's. Infrequent. 



Agnostus acutilobus, n. sp. (Plate VII. Fig. 10.) 



Body elliptical elongate. 



Cephalic shield semi-elliptical, somewhat longer than wide. Dorsal furrow lightly 

 impressed. Marginal furrow and fold sharply defined. Grlabella subconical, widest behind, 

 obtusely pointed in front ; at the wàdest part of the posterior lobe it is one third of the 

 width of the head shield, and its length is about three fourths of that of the head shield ; 

 the glabella is divided into four lobes, of which the anterior is one third of its length, and 

 is snbtriangular; the posterior lobe extends to the base of the shield. It bears an elonga- 

 ted ridge on the anterior half, where it is higher than it is behind ; two faintly marked 

 lateral furrow^s are just discernible on the lateral edges of this lobe. The two basal lobes 

 of the glabella are comparatively large ; they are divided from the rest of the glabella by 

 a sigmoid furrow, and are depressed below the leA^el of the glabella. The occipital ring is 

 narrow, and is concealed beneath the projecting posterior extremity of the glabella. The 

 cheeks are somewhat full, especially in front, and are divided by a furrow that connects 

 the dorsal and marginal furrows, and each cheek is seamed across by a fainter furrow. 



The thorax consists of two segments, of which the first bears five lobes ; the two outer 

 pairs of these lobes are globose, and the central one is semicircular and is crossed in the 

 middle by a light furrow transverse to the axis of the thorax. The second segment of the 

 thorax has three lobes, of which the two outer are somewhat elongate, and each is marked 

 by a light furrow ; the central lobe is subrectangular, and is traA'ersed by a furrow angu- 

 lated on each side of the axis of the thorax, and beginning and terminating on the posterior 

 side of the lobe. 



The pygidium is subelliptical, and its width and length are about equal. The marginal 

 fold and furrow are about as distinct as those of the head shield. The axis is oblanceolate, 

 nearly half as wide as the pygidium, aud its length is about four fifths of that of the 

 pygidium ; it is narrowed in the anterior third, and is crossed in that part by two trans- 

 verse furrows similar in appearance and direction to those of the preceding species. The 

 included lobe bears an elongated tubercle ; the posterior lobe of the axis is conical. The 

 lateral lobes of the pygidium are moderately elevated, and meet behind the axial lobe. 



Sec. IV., 1885. 10. 



