the infiltration of the dark matrix. Toward the base of the specimen this tubular 
part is very much contracted. Traces of the tubuli radiating from the axial 
part also are present. Figure 1 on Plate 32 is a cross-section of the same specimen. 
From the Black River limestone at Watertown, New York. Received from Dr, 
Rudolf Ruedemann of the New York State Museum of Natural History. 
Fig. 3. Actinoceras tenuifilum ursinum Var. nov. A vertical section exposing 
the siphuncle but not passing through the axial part of the latter. The cross- 
sections of this axial part, at the top and bottom of the specimen, show that it 
is dark in color like the matrix but very irregular in outline. Traces of the 
tubuli which radiate from the central axis are seen most distinctly where they 
approach the annular segments of the siphuncle, but a few cross-sections of these 
tubuli are visible near the axial parts of the siphuncle. Figure 6 on Plate 32 
is a cross-section of this specimen. The same specimen as Figure 5 on Plate XIII 
of HoltedahPs paper ‘‘On the Paleozoic Series of Bear Island,” 1919. From the 
Tetradium limestone of the Heclahook system on Bear Island, regarded as of 
Black River age. In the Palaeontologisk Museum at Kristiania, Norway. 
Fig. 4. -Actinoceras cf. tenuifilum centrale. A vertical section passing through 
the siphuncle. The latter apparently narrows toward the top. Figure 5 on 
Plate 32 is a cross-section of this specimen. From dolomitic strata of Black River 
age on either Boothia Felix or King William Land. In the Palaeontologisk 
Museum, at Kristiania, Norway; collected by Lieut. Godfred Hansen in 1903-04. 
PLATE XXIX 
Fig. 1, Actinoceras amundseni Sp. nov. A, ventral side of phragmacone, 
showing angular hyponomic sinus. B, opposite side of the same specimen, 
showing the siphuncle; the outline of the segments of the siphuncle are presented 
best by the lower part of the specimen. Figure 3 on Plate XXXII is an attempt 
at a restoration of its cross-section. From dolomitic strata of Black River age 
either on Boothia Felix or King William Land. In the Palaeontologisk Museum, 
Kristiania, Norway, Collected by Lieut. Godfred Hansen in 1903-04. 
Fig. 2. Actinoceras sp. A natural vertical section of the phragmacone, show- 
ing the ventral location of the siphuncle and its relatively large size. From 
dolomitic strata of Black River age on either Boothia Felix or King William 
Land. In the Palaeontologisk Museum, Kristiania, Norway. Collected by Lieut. 
Godfred Hansen, in 1903-04. 
