ulrich-bassler] revision of paleozoic bryozoa 289 



developed abundantly enough to simulate the radial clusters of the 

 other species. Vesicles apparently of slightly smaller average size 

 than in the associated A. siluriense of the same author. 



Occurrence. — Buildwas beds,Wenlock shales, Shropshire, England. 



ASCODICTYON SPARSUM new species 

 (Plate LXVIII, 15) 



This species is founded upon a single, but excellently preserved, 

 colony attached to a species of Polyporo. The vesicles contrast 

 strongly with the host, being much darker — nearly black. In form 

 they are ovate, appearing as highly inflated bulbs lying close to, in 

 some instances apparently in contact with, one of the extremely fine 

 threads that run in every direction over the surface of the Polypora, 

 though mostly parallel with the length of its branches. Generally 

 the vesicles are solitary ; sometimes, however, they occur in pairs, 

 while the interval between them is often greater than shown in our 

 figure. In size they vary from o.i mm. by 0.15 mm. to 0.2 mm. 

 by 0.25 mm. 



Belonging to the section of the genus having solitary vesicles, this 

 species need only be compared with Vine's A. filiforme. From this 

 it is readily distinguished by the smaller size of its vesicles and 

 greater delicacy of its connecting threads. 



Occurrence. — Near top of Chester group, Claxton, Caldwell 

 county, Ky. 



Cat. No. 43,142, U. S. N. M. 



ASCODICTYON YOUNGI Vine 



(Not figured) 

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

 xn, p. 90, pi. 4, figs. 3, 4. 



Original description. — " Zoarium composed of pyriform vesicles 

 occasionally disposed in stellate cluster, similar to other species 

 already described. These vesicles are connected together by fili- 

 mentous, hollow, unornamented threads, which creep along and 

 undulate with the irregularities of the surfaces to which the forms 

 are attached. The type species is adherent to a portion of a Crinoid 

 stem (Platycrimis sp.), and the stellate vesicles are not so abundant 

 in their colonial growths as in the Silurian species." 



Occurrence. — Carboniferous shales, Hairmyres, Scotland. 



Position Doubtful 

 Genus Ptychocladia new genus 

 Parasitic, small patches, consisting of bifurcating and inosculating, 

 transversely wrinkled, minute branches. 



