126 \ MICROSCOPY. \ 
inum, and was as large as the domestic cat, The existence o: 
peculiar forms of lizard, serpents and lemurs. constitutes points 
- of resemblance to the Eocene fauna of Wyoming not previously rec- 
ognized in our Miocene formations. 
Tue Genus Proromrerus.— This form of horse is character- 
ized, according to Leidy, by a peculiarity of the permanent teeth 
which belongs to the temporary teeth of Equus. Prof. Cope has — 
` recently obtained nearly complete skeletons of several species, 
: and finds that like Hippotheriwm they have three toes. He de- 
scribes a new species, P. sejunctus, in which the legs are consider- 
ably longer and the head relatively larger than in the true horse, 
, having thus proportions of body, as well as dentition resembling 
_ the colt. 
Senor’. 
consists eahatixily of a round hole # which the object is wedged, 
-acting beneath. Various forms are to be found that differ in size, 
but agree in principle, that of Beck being, perhaps, as convenieni 
as any, though I have used one consisting of a disk furnished 
` with a graduated series of holes and revolving so that any desire 
5 aperture could be brought over the screw, which, for making 
_ tions of stems was much more desirable. Dr. Hunt of Philade 
phia has the apparatus set in a freezing box, thus making 4 
refrigerating microtome, and by bedding animal structures in 
which expands and fastens them more strongly than parafi 
other compositions used for that-purpose, it answers very weit 
But having occasion to cut a number of plant tissues, especiat 
oe fern. stems, I found it very desirable to have oblique sections 
me show more perfectly the scalariform tissue, and the only way 
z -could VSSA this with the ordinary instrument was t 
: al crease in the flat sides of a split cork, to hold the 
1 ‘inserting the cork, cut the whole as one piece and s0: 
j forog from the cork. - Some tolerable sections were | 
| this way, but the results were generally so unsatisfac 
Twas led to devise a new instrument capable of more adapta 
the nstruction of which is shown in the accompanyl ng 
A and Pettis 5 surfaces ne my instrument of ge 3); 
