64 F, B. Meek on the genus Aviculopecten. 
ably typical of a ney: family, in which opinion Prof. Verrill 
concurs with me. r this genus I would propose the name 
Ethmophyllum. 
Among the specimens in the collection under examination, 
there are hogar two species of this fossil, That consid- 
ameter at the larger end, ‘and was ’ probably re to 6 inches or 
more in length, with 112 septa at the larger end. This large 
fragment shows that the septate outer zone does not increase 
in thickness or breadth in proportion with the size of the 
rallites, since it is only 0°15 inch broad in this ape the 
Guitene in thickness of this corallite being made up by the in- 
creased size of the non-septate interior. For this larger ioe 
cies I would propose the name ELthmophyllum Whitneyi, in 
honor of Prof. J. D. Whitney, to whom I am indebted for the 
use of the specimens. 
Of the other species I have seen but a single specimen, which 
is imperfect at both extremities, about 2°15 inches in length, 
and only about 0°20 inches in diameter at the larger end, an 
0°15 at the smaller, with some 24 to 28 septa. In addition to 
its much more slender form, it differs from the other species 
in having its septa so strongly waved laterally, as almost to 
divide the interseptal spaces into cells, nearly to the outer wall. 
For this, if it should prove to be a distinct species, I would 
propose the name Hthmophyllum graci 
The specimens were all obtained ~ Silver Peak, Nevada, 
and were discovered by Mr. Clayton. 
cccalakailaiaihennaat 
Art. XII.—WNote on the shell structure and ad Family affinities of 
the genus Aviculopecten ; by F. B 
Tw several former publications, I have alluded to the anal- 
oer, some of their characters, between the genera Aviculo- 
and Pterinea ; particularly i in the nature of their broad, 
rowed cardinal plate or area, without any well defined carti- 
lade pit. examining e shell structure of several spe- 
cies of ‘Aviculopecten, sometime since, Stereo ae able’ to 
detect any traces of the peculiar p 
