



500 PROCEEDINGS OF SCIENTIFIC SOCIETIES. 
are identical with those of the Atlantic, unless two Holothurians her 
may be regarded as peii though considered the same b S 
A careful ear study of the corals and Polyps of the Atlantic, 
and extensive, and, for the shallow water forms , nearly complete collec- 
tions from various localities on the Pacific c coast, give quite unexpected 
esults, since no species are found to be identical, while even the genera 
jx] 
u 
side, are represented, the last by two gigantic species. Among the 
Haleyonoid Polyps we find an equal contrast, for Eunicea, Plexaura, Plex- 
aurella, Pterogorgia and many other very common Atlantic genera are 
cies of Psammogorgia, Litigorgia, and Eugorgia, which are eminently 
characteristic of that coast. 
The genus Muricea is very common, and represented by seventeen spe- 
cies, while on the Atlantic side only four species are usually admitted, all 
of which are so different as scarcely to be regarded aš analogous species. 
The genus Renilla is found on both coasts. Among the Actinians we find 
greater resemblances, but as yet no identical Species. 
From these facts we may legitimately conclude rq no very extensive 
or deep connection, sufficient to alter the course of oceanic currents, can 
have existed since the coasts have been inhabited ne a existing spectet 
otherwise a greater admixture must have taken place. A narrow or shal- 
low channel of (^ spine Stan would probably Pici for all identical 
nae yet observed, but at what period it may have existed is still 
r question. The occurrence of certain Atlantic species in the Gulf 
it California and not at Panama (Codakia tigerina, Paphrydia agp 
the evidence of a uniform and long continued flow of the Gulf Stre 
be derived from the growth of the sanete coral reefs of the mn 
mudas, and the southern extension of Florida with its numeroüs ancient 

ested by the es and genera are 
probably facts of a different order, and will require a different solution, 
for even if we adopt a developmental mà we shall doubtless be 
pel : to refer the period of separation a period far more ancient than 
Which the few identical specie rael mg parated, and to admit 
a far more extensive | and prolonged connection aero the two 













