1888-89.] Mr F. E. Beddard on Anatomy of Phreoryctes. 119 
15. The spermathecce are present to the number of from two to 
three pairs in segments 7, 8 (and 9). 
The above characters show that Phreoryctes occupies an inter- 
mediate position between Earthworms and the lower Oligochaeta. 
It should form the type of a distinct family.* 
The paper concludes with a discussion of the morphology of the 
genital ducts and the classification of the Oligochaeta. 
Note on the Transformation of Ciliated into Stratified 
Squamous Epithelium as a result of the Application 
of Friction. By Dr John Berry Hay craft and E. W. 
Carlier, M.B., B.Sc. 
(Read January 21, 1889.) 
{Abstract.) 
In man, in the rabbit, and some other animals the trachea is built 
up of a series of cartilaginous rings incomplete behind ; the rings 
being completed in this position by the trachealis muscle. 
The mucous membrane forms a smooth cylindrical lining for the 
whole tube, and is covered by a ciliated epithelium. 
In the cat and dog the cartilage rings completely encircle the 
trachea, and overlap posteriorly, and the trachealis muscle, which is 
well developed, is placed outside the cartilage, and has a powerful 
action in varying the diameter of the tube. 
When this muscle contracts the overlapping ends of the cartilage 
ride one upon another, and the projecting ends form a vertical ridge 
down the inside of the trachea, which can be readily seen on slitting 
the organ open. This ridge is separated by a deep groove from 
the other end of the plate. 
The mucous membrane which lines the trachea is reflected in 
between the overlapping ends of the cartilage plates, and therefore 
will be subject to friction during their movements. 
That portion of mucous membrane which lines the tip of the pro- 
jecting ridge will be subject to the greatest amount of friction, and 
here we find that the ciliated epithelium which lines the general 
cavity of the trachea is replaced by stratified squamous epithelium. 
* It is so placed by Vejdovsky. 
