upper Ordovician at Vevay, Ind. — Cumings. 375 
young stages can usually be obtained. Specimens in the writ- 
er's collection, of a width of less than i mm., and even so small 
as 0.5 mm. are not infrequent. These together with similar 
developmental material from the zone of Dalmanella meeki 
higher up in the series await description in another place. 
Platystrophia biforata and its varieties has been discussed 
in detail in a paper by Mr. Mauck and the writer on a quanti- 
tative study of variation in this species. There could scarctely 
be a better locality than Vevay for the collection of adequate 
series of this interesting species, and especially of the so-called 
variety lynx. 
Raiinisqiiina alternata also exhibits minute variations from 
zone to zone culminating in the forni pondcrosa of the lyn v 
beds. This protean species would well repay quantitati\e 
study and here again Vevay would readily furnish suitable ma- 
terial. 
DESCRirXION OF NEW SPECIES. 
Dekayia magna, n. sp. 
PLATE XXXIV, FIGS. I TO 6. 
In form! and general appearance ths species closely re- 
sembles D. aspcra E. & H. The zoarium consists of irregula" 
flattened branches (as in the Lawrenceburg specimen) or mo^e 
frequently of robust frequently brandhing masses (as in the 
Vevay specimen) of a diameter of 40 mm. or more. Spines 
can occasionally be detected upon the surface. 
Tangental sections show that the cell walls are thin with 
usually a well defined median lamina. Acanthopores few. 
small. Diaphragms extremely few ; occasionally one or two 
near the svirface. 
Observation: This form might be considered as identical 
with D. aspcra but for the small size and less frequency of the 
adanthopores. 
Locality : Vevay and Lawrenceburo^, Indiana, in the Platystrophia 
laticosta zone. 
Dekayella cystata, n. sp. 
PLATE XXXV_, FIGS. I TO 6a. 
Zoarium consisting of flattened branches, at times 30 mm. 
or more in width. Surface covered with small conical monti- 
cules, about three in the space of 5 or 6 mm. Cells 0.2 mm. to 
