674 PROCEEDINGS OF THE NATIONAL MUSEUM vol.xxiii. 



the shell. These inner lamellee are oblique to the outer layer and are 

 arranged as imbricating' laj^ers, very much as in 0. favosa. 



A ventral valve 10 mm. in length has a width of 9 mm. A dorsal 

 valve 9 mm. long has the same width. 



The area of the ventral valve is of medium length and tipped l^ack 

 of the edge of the valve to meet the beak. It extends well out on to 

 the cardinal slopes of the valve. It is divided midway ])y a narrow 

 pedicle furrow that passes inward into a large cylindrical chamber, 

 closed at its outer end. The surface of the area is marked T)y rather 

 strong transverse stripe crossing the area and extending in and around 

 the pedicle slit and chamber. On each side of the pedicle chamber 

 there is a rather strong undercut which in the cast is replaced hy a 

 marked tooth-like projection. The area of the dorsal valve is narrow 

 and, as far as can be determined from the single cast, ver}' nuich like 

 that of 0. crassa. 



The casts of the interior of the ventral valves show a central visceral 

 area, very much like that in O. crassa; also two strongly marked vas- 

 cular sinuses that extend well into the middle of the valve. No clearly 

 defined nuiscle scars are shown on an}- of the specimens. Casts of the 

 interior of the dorsal valve give little satisfactory data in relation to 

 the muscle scars. The cast shows a part of the outline of the visceral 

 area, also the impression of the transmcdian muscle scar. 



Ohservations. — This species appears to be the European representa- 

 tive of 0. crassa, which occurs at the same relative stratigraphic hori- 

 zon at Troy, New York. The Swedish species differs from the 

 American in being slightly more elongate in outline and in having the 

 interior thickenings of the area more strongly developed. The exte- 

 rior surface also appears to be marked by stronger radiating lines. It 

 differs from O. atlantica and 0. chromatica in being a nmch more 

 robust shell, and in many slight details. O. j>rlstinus is more rotund 

 and convex. 



O. onohergl is associated with the Olenellus fauna in Sweden in the 

 Schmidt la toreUi zone. 



Format ion andlocallty . — Lower Caml)rian. Zone of Schmidt iator- 

 elli^ Bjorkelunda, south of Simrishamr, in a gray sandstone. Sularp, 

 near Lund, Sweden, in a brown sandstone. 



Received from Dr. Joh. Chr. INIoberg. 



OBOLELLA LINDSTROMI, new species. 



This species differs from Oholella mobergi in the more subacuminate 

 outline of the valves, the surface characters, and the interior of the 

 dorsal valve. The surface of 0. lindstromi is much like that of Bicia 

 gemma. 



The ventral valve occurs in a hard gray sandstone of the Schmidtia 

 toreUi zone, and the cast of the dorsal valve is from one of the brown 



