Geology and Natural History. 319 
(but previous to the publication of Mr. Miller’s pag proposed to 
substitute for it the name Opisthoptera, he did it only provision- 
ally, and bad not himself adopted it in the subsequently published 
Ohio report ; and (3) that neither Meek and Worthen jointly, nor 
Mr. Meek alone, had fully defined the generic characters o their 
type. 
No further notice ide be taken of the oe were . not 
that silence might be construed into acquiescence in views a 
practices that it is the sritaned t of all working net alists 3 dis- 
genera in different sub-kingdoms, or even in different classes of 
the same Pee: dom. This is the practice of some of the best 
and most renowned naturalists. Zroglodytes is constantly used 
for a genus of apes, and also for a genus of birds, an ca many other 
i b i i er, Wi 
that he did at first, namely, in case it should be found generically 
distinct from Amboryohéa and the name Meyaptera should be 
objected to. But it would not have altered the case if he had 
there said nothing about it, or even if he had gid eee to retract 
both Megaptera and Opis thoptera Se the nam 
Was published it became the rty vis science, pity he had no 
hot published, is no and cannot be, sus by 1 usag 
ven in recent zoology, where it is possible to ascertain clearly 
all the characters, no such rule is generally follow u 
rule would be utterly inadmissible in the department of fossil 
mainly or entirely upon external characters. The rales would en- 
danger the name Anomalodonta, because nothing is yet known of 
the pallial line said pedal mus seular scars of that shell, to say po’ 
ing about the extraordinary oe tion of 0 adductor impressi 
in Mr. Miller’s figure. Hundreds of cases might be mentioned of 
genera established upon piscine sicabterl 
nlike some other genera, Opisthoptera has its more conspicu- 
ous characters external, namely, its form and surface ornamenta- 
tion, which when taken together are quite sufficient to distinguish 
