June, 1906.] 
Key to the Order Thysanura. 
545 
Galium trifidum L. Woods, southeast of Laboratory. 
Juncus tenuis Willd. Edge of Bay near the Cedar Point Dock. 
Lathyrus maritimus (L.) Bigel. This species, between Rye Beach and the 
Black Channel, was collected by R. F. Griggs, 1903, E. L. Moseley, 
1904, and again by the writer, 1905. At Presque Isle, Erie, Pa., this 
species is very abundant. 
Lemna minor L. Ponds, Ridge Section. 
Lysimachia nummularia L. Near the lighthouse. 
Monarda mollis L. The most common Monarda on Cedar Point. 
Polygonum pennsylvanicum L. Marsh near Laboratory. 
Potamogeton amplifolius Tuckerm. 
Potamogeton foliosus Raf. Both the above species east of entrance to 
Biemillers Cove. 
Potamogeton lucens L. Near the Black Channel. 
Rumex altissimus Wood. Marsh north of “White House.” 
Sagittaria graminea Mx. Opposite Laboratory at western edge of 
Biemillers Cove and near the “Carrying Ground.” 
Thalictrum polygamum Muhl. Edge of marsh near the Black Channel. 
— Toxicodendron pubescens Mill.^ On sand dunes near Laboratory. 
Prof. E. L. Moseley® in listing the vegetation of the bar between the 
Black Channel and Rye Beach mentions the following species, none of 
which were included in the “Flora of Cedar Point”: 
Equisetum pratense Ehrh. 
Gentiana andrewsii Griseb. 
Liriodendron tulipifera L. 
Muhlenbergia mexicana (L.) Trin. 
Solidago canadensis L. 
1. Kellerm.^n, W. a. and Jennings, O. E. Flora of Cedar Point. 
Ohio Nat. 4 : 186-190. June, 1904. 
2. Greene, E. L. Segregates of Rhus. Leaflets, 1 : 114-144. Nov. 
24 and Nov. 29, 1905. 
3. Moseley, E. L. Formation of Sandusky Bay and Cedar Point. 
Proc. Ohio State Acad. Sci., 4 ; 179-238. 1906. 
Carnegie Museum, March 28, 1906. 
KEY TO THE FAMILIES AND GENERA OF THE ORDER 
THYSANURA. 
C. F. Jackson. 
The order Thysanura comprises on the whole, a group of 
very small insects, the largest of which do not much exceed 
25 mm. in length. They may be found in almost every con- 
ceivable locality, under old logs, in moss and grass, along the 
margin of stagnant pools and even in our dwellings. A"et 
strange to say since the time of Degeer, Nicolet and Sir John 
Lubbock but little has been added to our knowledge of Thysa- 
nura and the study of this most interesting order of insects has 
till within the last few years been very much neglected. 
As in all other branches of science, much confusion has arisen 
as to the identity of species. This is due partly to the fact that 
the descriptions given by the early writers are frequently so 
short and incomplete that the species, or even the genus, cannot 
