H. J. Clark on Lucernaria. 349 
as I have described them in Prof. Agassiz’s third volume of his 
“Contributions to the Natural History of the United States.” 
In the oral or lower side of the disc of Aurelia, the gelatiniform 
substance has the same structure as in the aboral side, while in 
Lucernaria, although it has all the regularity in the disposition 
of its components that obtains in the aboral side, yet it possesses 
a totally different nature, as I will describe hereafter in connee- 
fion with the muscular system. 
From the middle of the base of each of the four flat sides of 
distal ends through the narrow passage between the terminus of 
end of each partition, triple or quadruple rows of slender digiti- 
ies extend each way for a considerable distance along 
the border of each half of a genital, thus forming the common 
Way to the surface of the body, each fibre forks two or three times, and then one 
Ment at this age, although occasionally one of the prongs of the fork is absent, or 
only partially developed. Sometimes each prong forks again, at a narrow or wi 
From the tenta 
| ube. 
a few are all the fibres, however, that with a casual glance they might be mistaken 
. = a unimportant streaks here and there, se of such methodically arranged 
A. Jour. S8c1.—Szconp Series, VoL. XXXV, No. 105.—Mav, 1865. 
45 ; 
