400 OLDER MESOZOIC FLORAS OF UNITED STATES. 
buds; rock substance soft except where excessively mineralized, light 
ash colored with dark, sharply contrasting stripes and spots, usually 
of low specific gravity; organs of the armor mostly ascending and 
adjusted to the axes of the branches; phyllotaxy not generally trace- 
able except in secondary arrangement around certain branches; leaf 
scars subrhombic or somewhat elliptical, 15 to 20 mm. wide, 8 to 12 mm. 
high; leaf bases dark and affected with white fistular punctations; 
walls 2 to 4 mm. thick, soft-sandy, white or yellowish, striate, often 
with a median groove, depression, or crack; reproductive organs some- 
what rare, often well-developed, either flush with the surface or raised 
above it, elliptical in cross section, variable in size, 15 to 30 mm. in 
diameter, surrounded by large triangular bract scars, the central por- 
tion solid and marked by the scars of the essential organs; armor 4 to 
6 cm. thick, joined to the axis by an uneven, more or less definite line; 
wood 2 to 3 em. thick; cortical parenchyma 1 to 2 cm. thick; fibrous 
zone 1 to 2 cm. thick, sometimes in two rings with radiate structure; 
medulla 3 to 6 cm. in diameter, fine-grained and homogeneous. 
This species is one of the most common in the Jurassic of Wyoming, 
and is typical of the smaller branching forms. It embraces Nos. 
500.5, 500.23, 500.80, 500.36, 500.38, 500.41, 500.49, 500.70, 500.77, 
500.78, 500.80, and 500.82. Nos. 500.49 and 500.77 fit together, and 
No. 500.41 evidently belongs to the same trunk. A small piece has 
become detached from No. 500.49. Nos. 500.78 and 500.82 also fit 
together, and No. 500.70 seems to form a cap to this small trunk, but 
a portion is lost between them. The rest are all single. Nos. 500.5 
and 500.23 are practically complete trunks. Nos. 500.36 and 500.38 
are parts of two of the largest trunks of the species, and No. 500.30 
is over half of another nearly as large. They are all very handsome 
specimens, presenting the regular mottled striped or spotted appear- 
ance due to contrast between the dark leaf bases and the light-colored 
walls. No: 500.23 is nearly unbranched and is anomalous in several 
respects. It may represent a different species, but can not be identi- 
fied with any other specific group. 
The weights of the specimens are as follows: 
Kilograms. 
ING: DOOD wccnwneniwnewnieand ip ical oye VA A Sta tapeg ees AOD Ce NE 2.41 
INGOs, BO OI 28 seraseteeencs. 2:2 terse anctawn eciiecerieemeate tetas ah deceiver ese tate eel eens 1.05 
No: 50030 edcaw sees omemaca nes xiv si erieircoews ove cteremnieeses ceielcs 2.30 
NG: 000286 sic.cc0s's ecdeoreanecec cae ees eas. oumnnes sea 8.43 
ING DOOESS'2.2i0.052 a 2.iceeSinciescied da: eimeuinwe hoa es SRE cei 3. 32 
IN ON OO TE sc goss Sa pscereu sa ananeyn ecne icv es aecy ona cidaue 2s saveucloucae peysie eee 0.37 
NG's BOO ora e era ie z sierersictararerersinis te secarsnvesad ein w she accra ieee 1. 84 
Wii HOU ones cee merivanaus as ameqemeunecicn demeecenicies seis 0.56 
ING: D00SK o,-.dcc cote baeer Sees eee tes teewemsemer see eee 1.14 
Bi. BOO UEG iat op cieetm enw se nainthuitic EAL EC ERAN Byam 0.79 
No. 500.80 -..--- wanes Paiedoand ae ARE aera er eRe aT 0.79 
Wi BOOB aioe e < vigsaroctinrnie Sr cs gases wrath istered 0.62 
