MICROSCOPY. 497 
But the most valuable of Professor Marsh’s papers is the last, 
which appears in the “Journal of Science” for June. It is a re- 
view of the ‘“ Structure of the Skull and Limbs in Mosasauroid 
reptiles,” made possible only by the richness of the Yale Museum 
inthe remains of these remarkable animals. Though this paper 
is almost entirely a technical one, yet the results are obviously 
of high scientific interest. Prof. Marsh shows that the quad- 
tate bone of the skull as given by Professor Cope should be 
reversed, by finding a skull of Lestosawrus with this bone in posi- 
ion. Moreover, his explorations have discovered the stapes, the 
columella, the quadratoparietal arch, the malar arch and the 
pterotic bone, belonging to the cranium; and have proved the 
exact character of the anterior limbs and the presence of poste- 
rior limbs in these reptiles. They also show that the neck in the 
Mosasaurus group was unusually short. Two new genera, Lesto- 
saurus and Rhinosaurus, are described; under the former, four 
new species are included. Rhinosaurus micromus Marsh an 
Edestosaurus rea Marsh, are also here described. The paper is 
illustrated by four admirable lithographic plates. 
MICROSCOPY. 
_ CELLs ror Movuxtine Opsecrs.— A recent discussion on this 
Subject at the Queckett Microscopical Club in London, developed 
several important suggestions. 
; Lead cells. Mr. James Smith introduced the subject by a paper 
On Cell Mounting.” He used cells of sheet lead; flattening 
the sheet on a plate of glass by rubbing with an ivory paper knife, 
and cutting or punching cells which were subsequently flattened 
by pressure between two ordinary glass slides. Dr. Matthews 
Suggested flattening the lead upon a plate of glass, by rolling, 
and cross rolling, with a piece of barometer tube. The Chairman, 
Henry , Esq., remarked that Dr. Bowerbank had for years 
used exclusively tea lead for his smaller cells and common plumb- 
— — for his larger cells: all his large collection of sponges 
a ic Successfully mounted in this way. The secretary, Mr. T. C. 
hite, had been in the habit for many years of using cells of thin 
sets known as “ pattern lead” used by dentists ; the cells being 
easily: stuck on with marine glue, and not melting if the slide 
wuld be made nearly red-hot. 
AMER. NATURALIST, VOL. VI. 32 
