212 F. B. Meek on the Family Pteriide. 
higher telescopic power resolves previous nebule? It is very 
doubtful whether our best telescopes will ever be able to bring 
lous matter in the vicinity of our system, either planetary or 
stellar, and ages may pass before our system, in its a 
through space, will come near any of the small patches that may 
exist, so as to render them visible to us. 
Perry City, N. Y., Aug. 31st, 1863. 
closely connected with the period of the solar spots. It is also 
known that the auroras influence the needle; and that they are sub- 
ject to the same law of periodicity as the solar spots; and thus 
seem to be connected with solar influence. The effect of the 
auroras is evidently light-producing. 
a 
Art, XX.—Remarks on the family Pteriide, (= Aviculide) wilh 
descriptions of some new fossil genera; by F. B, MEEK. 
THE existing genera of the family Pteriidx form a group a 
once so natural, and so distinctly defined, that conchologists meet 
with little difficulty in deciding what particular genera it should 
include." When we undertake to classify the more numerorm 
extinct genera, however, which were introduced, lived out thet 
term, and passed out of existence at various periods during Wt 
immense interval of time between the first introduction 0 this 
presenting various intermediate gradations between the moder! 
* Perhaps the only question in regard to the limits of this family, as known it 
our existing seas, respecting which late writers on conchology differ, 1s, wheth : 
ee  incinde t i e think it should, while otbers make 
sie IN see Soe 
differs in not having its beaks terminal, but set back some distance from the “a 
obtusely pointed anterior extremi The beaks, however, are de eens 
scarcel distinct from the cardi y of the shell 
scarcely : inal margin, and the general aspect of the 
to be intermediate between that of Pinna, and Avicula 
pero Hed know whether or not it has a prismatic structure ; if not, 
probably be found to belong to the Mytilide. 
