WARD.] JURASSIC CYCADS FROM WYOMING. 405— 
irregular on its outer, even on its inner face; fibrous zone consisting 
of three very definite exogenous rings of wood, the outer 5 mm. thick, 
the middle one 2 mm. thick, and the inner one 1 cm. thick, all with 
radiate structure, the medullary rays visible across the entire zone, 
the inner wall of which is scalloped by the rounded inner edges of 
definite woody wedges, 8 mm. wide, and the sharp reentrant angles 
between them; medulla when circular 4 cm. in diameter, when ellip- 
tical 38 by 5 cm., in one specimen 5 by 7 cm. in diameter. 
This species is represented by seven different numbers in the collec- 
tion, but Nos. 500.13 and 590.72, Nos. 500.44 and 500.78, and Nos. 
500.53 and 500.61 each match and complement each other. No. 
500.37 is larger than the rest and represents most of the lower part 
of atrunk. With the exception of Nos. 500.53 and 500.61 all the 
specimens so closely resemble one another that the suspicion arises 
that they may all belong to the upper part of No. 500.37. Butacareful 
examination negatives this view, and it seems necessary to suppose 
that they represent at least two different trunks. The combination 
Nos. 500.44 and 500.73 may be a part of the same trunk as No. 500.87, 
but the combination Nos. 500.13 and 500.72 must be distinct, as it 
forms nearly half of a trunk of different shape, with the large mammil- 
lary terminal bud and a small portion of the base, which show that 
this trunk was low and vertically compressed, if at all. 
The combination Nos. 500.53 and 500.61 constitute more than two- 
thirds of a handsome little trunk, broken longitudinally through 
the center of the axis and one of the halves tranversely above the 
middle, the fractures being as clear and perfect as if sawn. This 
specimen shows the internal structure more perfectly than any other 
in the collection, especially the three exogenous rings of wood, as 
described. 
The weights of the specimens are as follows: 
Kilograms. 
NOMO00 1 Orig Sieben bootie jake See Shae eae eaeiNas eee aS 1.08 
INO? D000 nc) eee cee oe eee Vee eee mE eee se 2.41 
Nos: 00:44 oc aenectouass haces emees cenecitaess pe esewiee ess seee% 1,25 
ING: 00058 2532 dctinsuers Mag eee Stee eS aes eee tease es emeaeeie vente 1.64 
ING DOOLGT aoe os cpheed Eeatie. oe everepnctdise d wlatceiyauaidiee aie steimpeicigeeins Sa 1.16 
INO DOO 72 oa cara 2 tes ohailasmvaro 8: Sentai Sfercasjens) & a's eierravereinie ae bate SBiste Ses seke 0.59 
ING DOONTS wate See eecienecrespeiten mrt Cee iralsl alese ada ceenle iat si5 oe 0. 65 
Pl. CX XX shows the back or outer surface of No. 500.53 and Pl. 
CXXXI the base of the nearly complete trunk resulting from the 
complementary Nos. 500.53 (a) and 500.61 (6). Pl. CX XXII illustrates 
the internal structure of the same trunk, Fig. 1 being the longitudinal 
section offered by No. 500.53 and Fig. 2 the transverse section of No. 
500.61, which has already been described. Pl. CX XXIII illustrates 
in a similar manner the combination Nos. 500.13 (a) and 500.72 (0). 
Fig. 1 is a somewhat oblique view, showing the terminal bud and outer 
