KONGL. SV. VET. AKADEMIENS BANDLINGAB. ItANI) 34. N50 8. 17 



Another of the new species is one that Liljevall has found a1 Korpklinl near 

 Wisby (Pl. II figs. 11 — 16). The hypostoraa is more elongate fchan fcransveree with the 

 anterior margin regularly arcuated, by far no1 so prominenl as in B. sulcatus and the 

 former. By ;i shallow groove the exteriör surface is divided in two fields, the anterior 

 one the largest and covered with ;i few, distantiated, concentric terrace lines. The pos 

 terior field is smooth, nearly even and the maculae lie just in the groove, with their axis 

 oblique to the longitudinal axis of the hypostoma, beanshaped and smooth. The cephalic 

 eycs show in a horizontal section hexaedral white walls enclosing a dark space in which 

 some indistinct radii emanate, fig. 41 a. In the vertical sections the prisms are narrow 

 and elongate and the integument by far not so thick as in Bumastus sulcatus, fig. 12, 13. 

 The börder zone of the eye in this (fig. 41) as well as in 15. sulcatus, as seen in hori- 

 zontal sections, agrees with that of the Asaphidae. 



Bumastus sp. indet. 



Pl. III fig. 1, 2. 



In a detached piece of limestone, fonnd in Gotland, at Norderstrand, uear Wisby, 

 two hypostomas and a free cheek lay embedded along with a coral of the genus Acantho- 

 lithus and a Bronteus probably belonging to a new species. As the coral has not been 

 found above the uppermost beds of the Lower Silurian it is probable that the trilobites 

 also are derived from the same horizon. 



The hypostoma, figured pl. III fig. 1, is broadly tongueshaped, with a short, blunt, 

 triangulär wing on each side of the anterior margin. The exteriör side is nearly 

 completely occupied by a single lar ge field, which is convex and decorated by sparse 

 terrace lines. Below this a smooth, nearly even plane, reaching to the inferior, elevated 

 horder of the hypostoma. The two tubercular macula' are situated exactly on the bound- 

 ary line between the convex and the plane field. They are elongately ovate, pointed 

 outwards, rounded inwards, with smooth and glossy surface. That portion, on which in 

 the species of Bronteus the granular spöt rests, is transversally wrinkled by some faintly 

 elevated, sigmoid lines (fig. 2). It would have been of great interest to investigate the 

 interiör structure of these curious maculae, but the scarcity of the material has prevented 

 our doing so. 



The other hypostoma, pl. III fig. 3 — 5, is larger and has the terrace lines more 

 distantiated and forming more open curves, but for the rest it is of the same shape as 

 the smaller, so that we may not ascribe these small deviations to a specific difference. 

 The maculae are more elongated, narrow, curved tubercles, thus differing from the next 

 preceding. A section running through its left tubercle does not show any structure, but 

 the shell of the macula' is extremely thin, thus contrasting strongly with the surroundiiig 

 thicker shell, fig. 4 a. The cephalic eye, again, remaining on the free eheek found in 

 the same piece of limestone and probably belonging to the same specimen, has its surface 

 well preserved and exhibits serniglobular lenses in low relief, fig. 5. 



