vine: YORKSHIRE CAKBONIFEROUS and PERMIAN PoLYZUA. 191 
Of late)^ears very great attention has been given to the proper 
classification of the ovicells of tlie Cyclostomata especially, and it 
behoves every worker on the snb-order to help to throw all the light 
l)ossible on this most interesting, bnt at times very difficult subject. 
Classifications serve their day, but structural elements and structural 
peculiarities in any form are valuable aids in zoological investigation, 
but the proper definition of these elemental structures may help to 
serve as adjuncts for a higher appreciation of varietal changes in a 
species, both in time and space, than we now possess. Ovicells in a 
species tell a far more reliable tale than the robust or diminutive cell 
is capable of telling, hence their impDrtance in the definition of a group. 
Genus Streblotrypa, Ulrich. 
III. Geological Survey, vol. viii. (Aug., 1889, still unpub.) 
Slreblotrypa uicklisi, Ul. (MS. 1883 ?) pi. vii., figs. 6 and 7. 
1883. /S'. nicklisi, Vine, Proc. Yorksh. Geol. Soc, vol. viii., p. 107, 
pi. xxi., figs. 4 and 5. 
1887. >S'. nicklisi, Ulrich, III. Geol. Survey, Illinois, vol. viii., 
figs. 9 a to c. 
Unfortunately I cannot redescribe my Yorkshire example of this 
beautiful species, as the fragment which was described and figured in 
the Proceedings cited above, is evidently lost. For the purpose of 
this monograph I have re-examined all my Yorkshire Polyzoa, and I 
was sorry when I came to this species for redescription and found that 
my specimen was gone, though the place on the slide showed the 
vacant space where it was once attached. I have to rely in conse- 
quence on my previous work. ''The small fragment was about li 
lines in length, and about i line in width. In the whole length of 
the fragment, taking a row of cells, I find there are about 7 cells, or 
being more accurate, 6i cells [to the li lines]. A fragment of the 
American form of the same dimensions, for some specimens are more 
bulky than ours, affords the same results."" 
In the note already cited from Mr. Ulrich's " Waverley Bryo- 
zoa," the author quotes from my Yoredale Polyzoa paper,t and he 
^ Vine, Proc. Yorks. Geol. Soc. 1884, vol. Iviii., p. :08. 
t Vine, Proc. Yorks. an l Pol>t. Soc, vol. ix., pp. 1-29. Since Mr. Uirich 
has publifshed details of bis specien, S. Nicklisi, Ul , I think it wise to alter the 
British reference thus : Strebbtrtjpa viinuta. Vine ( = aS. Nicklisi, Ul., var. 
iinnuta, Vine) The figures in plate x., figs. 7 to 9, are not good, and at some 
future time will be redrawn. Of this species I have about seven examples. 
