278 The American Geoloyiiit. November, 1S97 
posing the genus Palceophyllum demand admission to this long 
list of synonyms, since they are evidently based upon mistak- 
en distinctions. 
The little known Streptelosma expcinsmn Hall is technically 
the type of the genus, but S. cornicuhim Hall as described by 
Edwards and Haime has been virtually the type species, and 
both of them are not yet distinguished from an older named 
species S. profiindum (Owen). With very little doubt they 
are synonyms and S. profundum would therefore be the name 
of the type species. 
Since iirst described, S. expansmn Hall has remained a 
nearly unknown species. There has likewise always been doubt 
as to the true nature of the species S. cornimduv} Hall. No 
one could have recognized 8. profnndiim (Owen) had there 
been an associated species. 8. corniculum as described by 
Edwards and Haime, by Kunth and by Nicholson was the *S'. 
rusticum Billings, and not 8. corniculum Hall. Not improb- 
ably the meagre descriptions and imperfect knowledge of 
these corals is all that has kept them from being recognized 
from the beginning as synonyms. The same cause has evi- 
dently permitted the coinage recently of even more of these 
species. 
James Hall in 1847 described several species, viz. : Strepte- 
lasma profundum (Owen) Hall, 8. corniculum Hall, 8. eras- 
sum Hall, 8. multilamellosum. Hall, 8. 2^fi^'vulum Hall, and 
8. expansum Hall, but Edwards and Haime (1851) in their 
great monograph recognized only 8. corniculum and reduced 
8. crassum, 8. multilamellosum and 8. 2^(^^'vuh(7n to the rank 
of synonyms. 8treptelasma exjiansum Hall and 8. profun- 
dum Hall they reported as doubtful. Billings (1857) on the 
contrary aimed to recognize all the above named and later 
made more of them, 8. rusticum (Bill.) in 1858, and 8. aper- 
tum (Bill.) and 8. angulatum (Bill.) in 1862, besides Palceo- 
phyllum rugosum. Bill, in 1858. 
Nicholson (1875-89) has followed the example of the great 
authors, Edwards and Haime, except that he described Pala;- 
ophyllum divaricans Nich., 1875. Recently E. O. Ulrich(1893) 
has made two more species, 8. parasiticum Ulrich, and 8. 
breve Ulrich. Winchell and Schuchert distinguish 8. ptro- 
fundum^ 8. corniculum and 8. rusticum besides admitting Ul- 
