No.iui. FOasiL VVCAIJS FROM THE liLACK HILLS— [VAUl). 225 



lateral comprcHsioii, badly worn like the others, and haw a slab Hcaled 

 oHfrom one side, expoHiiif^ tiie outer Miirface of tiie inediilla and vxnva 

 Hjiondiii;;- iiiinn- wall of the w<>o<ly /one. ThJH speciuKju is .'V.) (;ni. hiyh, 

 15 by 1^0 <;iu. in dianicLer, and has a yirth oC 51 cm. Its ellipticity is, 

 liowever, exa^/^erated by the greater erosion of the flat sides. 1 1 \v'ii<,'hs 

 12.7 kg. 



No. 105 is oidy a section, weighing 12.H kg., with base and summit 

 wanting, also a piece from one side, part of which was saved, but the 

 part that remains shows the outer surfac<; in th(i most perfect state of 

 preservation, and ukujIi of the above d(!S<;rij)ti(>n ol" llie i>liyilotaxy, 

 leaf scars, petioles, vascular bundles, ramentum walls, etc., is derived 

 from it. No. 107 is also an exceedingly interesting specimen, weighing 

 0.07 kg., and is especially valiuible as showing the true bas<5. It is 

 obli(iu<!ly broken through (Vom the toi) to near the bottom, but one si«lc 

 shows the spiral rows of leaf scars. No. ll!i, although larger, weigh- 

 ing 14.20 kg., is not as well preserved, but also shows the base, which 

 is slightly concave. 



Ul)on the whole, this species may be regarded as one of the best 

 characterized of all that have been based on cycadeau trunks alone.- 



CYCADEOIDEA EXCELSA, new species. 



Trunks tall, compressed cylindrical (only specimen known 01 cm. 

 high and truncated), with an enlarged base, 112 em. in circumference at 

 th« base, 80 to 00 cm. at all other [>ointH, light ash-colored without, 

 whitish or bluish within, soft externally, line graine<l inside and mo<l- 

 erately hard, with the specific gravity rather low, unbranched but 

 more or less iiregular, crooked, zig/ag, and inclined; organs of Ihe 

 armor horizontal, or at right angles to tlui axis; leaf scars disposed in 

 two series of spiral intersecting rows, those from left to right making 

 an anghi of 20^"-, those from right to left of 50^^ with the axis; scars 

 imperfectly rIiombi(5 or rectangular, the diagonals HJ to 25 mm., th<i 

 lateral angles lu^arly alike, the vertical ones usually unlike, the upi)er 

 consisting of a deep but obtuse sinus, the lower also obtuse but rela- 

 tively shallow, sometimes reduced to a gentle concave curve formed by 

 the two lower si<l<;s; leaf bases generally preserved f;0 within 2 cm. of 

 tlie surface, disarticulated at a natural Joint, its siiif'ace (;ven and con- 

 cave but roughened and affected by many small dots of a dark color, 

 irregularly aiianged, peihaps r(;i)r(isenting gum ducts, and some hw^c 

 l)its wliicli may have (contained leaf bundles; ramentaceous walls thin 

 and frail, 1 to 2 mm., of a light color within contrasting with the 

 darker leaf bases, thi(5kened at the angles and more or less (jompound, 

 with a few small i)its repiesenting scars of l)ra<;ts or peruhui; repro- 

 ductive organs numerous, usually solid, harder than the remaining 

 parts, hence often projecting from tin; eroded surfaces, of <lifferent sizes, 

 the smaller ones probably al)ortive and occui)ying angular spaces 

 among the leaves, the walls dividing and surrounding them, circular iu 

 Troc. N. M. vol. xxi 15 



