448 0. C. Marsh—Structure of Mosasauroid Reptiles. 
It will be seen, in view of what has been stated, that two 
primitive molecules of the same substance should ‘seldom, if 
ever, unite unless their envelopes are brought by heat, ora dis- 
turbance of electric or mechanical equilibrium, into different 
conditions of expansion or electric accumulation. In fact, soli- 
dification appears in all cases to begin at certain points of the 
iquid mass, as the result of thermal or other changes, and pro- 
ceed outward from these points, from molecule to molecule, 
along certain lines of direction. 
(To be concluded.) 
tT. LXIL.—On the Structure of the Skull and Limbs in Mosasau- 
roud Reptiles, with descriptions of new Genera and. Species; by 
O. C. MarsH. With Me Plates. 
ou 
points in the structure of these pale in addition to those 
already announced,* and also to correct some errors of previous 
observers who have written on the subject. ‘These new results, 
here Ries recorded, will be more fully discussed in a future 
te bone in this group, in ‘affording generic and specific 
c acta was first recognized by Prof. E. D. Cope, to whom 
science is so largely indebted for its ee knowledge of this 
most interesting order of vee In his valuable Synopsis of 
a number of terms to designate its most charac aracteristic pany 
which were well ‘tlaetented™ by figures in different portions 0 
the work, and in some of his more recent publications. In 
ve position there assigned to the quatre in the aba it 
* This Joumal, vol. i, p. 44, Ps 1871, and vol. iii, p. 290, gy 1872. a 
t Synopsis, ~ am and Proceedings American Association ience, 
xix, pp. 217 and 2 
