284 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vOL. 45 



This species is distinguished from A. zvaldroncnse, which occupies 

 a nearly equivalent geological horizon in America, only by the larger 

 average size and rather more regular form of its internodes. In the 

 matter of size it agrees more nearly with the Devonian A. fusiforme 

 (Nicholson and Etheridge, Jr.), but its internodes are rarely, if ever, 

 isolated, and when normally developed they are bottle-shaped rather 

 than fusiform. 



Occurrence. — Silurian, Island of Gotland. 



Cat. No. 43,127, U. S. N. M. 



ALLONEMA FUSIFORME (Nicholson and Etheridge, Jr.) 



(Plate LXVII, 8) 

 1877. Ascodictyon fusiforme Nicholson and Etheridge, Jr., Ann. & 



Mag. Nat. Hist., ser. 4, vol. xix, p. 463, pi. 19, figs. 7, 8. 

 1892. Ascodictyon fusiforme Vine, Proc. Yorkshire Geol. & Polyt. Soc, 



vol. XII, p. 89. 



Plate LXVII, 8, represents the greater part of a very characteristic 

 example of this species. Often many of the internodes or vesicles 

 are quite isolated, but more generally they j*st touch one or more of 

 their neighbors. The most common shape is fusiform, others ovate, 

 while a greater or smaller number in each colony are joined together 

 by rather long necks. As usual in species of this genus, the whole 

 surface is distinctly punctate, but in no case have we observed a point 

 where an erect zocEcium might have been attached. 



The principal distinctive features of this species are the frequent 

 isolation of the internodes and their normally fusiform shape. 



Occurrence. — Hamilton formation, Alpena, Michigan ; Falls of the 

 Ohio; Thedford (Widder), Ontario. 



Cat. No. 43,129, U. S. N. M. 



ALLONEMA? MINIMUM new species 

 (Plate LXVII, 10-12) 

 Small colonies consisting of frequently bifurcating series of sub- 

 globular, ovate, or more or less elongate pyriform vesicles, generally 

 about 0.1 mm. in width and varying in length, according t© the 

 degree in which the proximal end is drawn out, from o.i mm. to 

 0.28 mm. The pyriform cells usually carry a minute pore and 

 remind of the zooecia of Ordovician species of Stomatopora, like .S". 

 infiata. No pores of any kind were observed on the subglobular 

 vesicles. Aside from the single pore that occurs on most of the pear- 

 shaped cells, these also exhibited no trace of the surface punctation 

 observed in all the other species referred to this genus. 



