90 
VINE: NOTKS ON YOKEDALE POLYZOA. 
23. ThAMNTSCUS GKACILiS new sp. pi. X., figs. 6-6a. 
Size of Zoarium unknowa ; branches flattened, dividing" 
irregularly, Zoo&cia on one side only, and with from three to four 
rows of cells in the brand), cells immersed, apertures circular, 
peristome slightly prominent, delicately tuberculated, with from 
eight to ten tubercles, occasionally one or two rather larger than the 
others in the circlet, about six cell apertures in the space of a line, 
intervening spaces between the cells likewise tuberculated. Reverse 
concave, very rarely rounded, stiiato-granulate, with from four, six, 
eight, or ten rows, according to the size of the examples. 
Localities : Yoredale, Gleaston Castle. 
This beautifully ,<iTac^>ful polyzoon T have not previously met 
with in any of my British shales. It is fairly abundant in the North 
Lancashire shales. There is in the American rocks a very peculiar 
species w4iich Mr. E. 0. Ulrich has pi ovisionally named — though not 
described — Stenopea gracilis (MS), but the distinctive features of the 
American forms are w(>ll marked, and could not, except in the delicacy 
of the branching, be confounded with the present species. It 
appears to me, however, that the American form may be fittingly 
placed among the Thamniscidi^. 
24. Thamniscus Eankinei (?) Young & Young. 
I place here a few fragments of a species of Thamniscus, 
doubtfully akin to the above well-marked species. 
Locality : Yoredale, Holker Park. 
Sub-Order, Cryptostomata, Vine. 
1883. Fourth British Assoc. Report, Fossil Polyzoa. 
1884. "Naturahst," October, p. 65. 
Zoo&cia tubular, sub-tubular, in section (occassionally) slightly 
angular. Orifice of cell surrounded by vestibule, concealed. 
Family RtlABDOMESONTiDiE, Vine. 
1883. British Association Fourth Rep. Foss. Polyzoa. 
1884. Rhabdomesoatidse, Ulrich. Jour. Cincin. Soc. Nat. Hist., April, 1884. 
This family was founded for the purpose of receiving the two 
species of Millepore of Phillips, which were more fully described by 
