H. J. Clark on Lucernaria, 347 
atrophy of these organs; and that this fact is to be classed in 
the same category as the occasional development of one of the 
tentacles into a semiauricular body. I have always noticed that 
individuals in such a condition have an unnatural appearance; 
that they are not so lively as the others, and appear to be dis- 
I believe this species to be identical with Z. auricula® 
of the English coast. The most characteristic figure that I know 
of, although unsatisfactory, is in Gosse’s little book, The Aqua- 
rium. 
In order to contrast the structure of Lucernaria with that of 
the Steganopthalmatan Meduse, and, moreover, in order that I 
lia flavidula Agassiz. The aboral side, which corresponds to the 
So-called dorsal region of other Acalephs, projects at the apex 
Into a moderately long columnar body, usually called the pe- 
uncle of Lucernaria. ith the exception of the four equi- 
distant channels and the four muscular cords which alternate 
with them, the peduncle isa solid gelatiniform mass, covered 
y the outer wall. This gelatiniform substance also constitutes 
ulk of the disc, filling the entire space between the outer 
Wall and the inner or lining wall of the digestive cavity, and is 
directly continuous with that in the peduncle. In Aurelia, 
Cyanea, and other Acalephs, this substance appears like an 
’morphous gelatiniform or semicartilaginous mass, with a few 
Uregular cells scattered here and there;* but in Lucernaria it 
é I have found such specimens most frequent at that time of the year which is 
ding season of our coramon shore-crab,— Cancer Platycareinus) irroratus, 
cles j The mom Luce 
“*s inward, but the reverted auricles are left exposed, and 
by the act than usual, and a conspicuous morsel for the predaceous creature. As 
season ad s toward er, the bunches of tentacles also disappear one 
after another, until it becomes quite common also to find individuals with two, 
three, or four bunches bitten off; and at the same time epee come more 
é Te More rare, at the last of June, for instance, and finally, by the early part of 
thie” it is impossible, by the most diligent search, to find a single specimen. As 
that ‘ppens at the ti hen the Lucernarians are laying their eggs, it is clear 
the the destruction of the adult does not necessarily annihilate the race. —_ 
ie Rext two months no Lucernarians are to be found, but in the last of August 
“ave collected young ones, much less than ;!, of an inch in diameter. 
: telystus auricula H. J. C., Journal Boston Soc. Nat. Hist., March, 1868, page 
‘. 
The original figure by Rathke, Mill. Zool. Danica, iv, 1806, pl. clii, althou 
os Sufficien correct Se eieaisenten can neither be called deeiduis nor g ful 
4s far as attitude is concerned, 
aS In June, 1862, I made a careful study of the structure of the e geitniiorm sub- 
_ Stance of Aurelia flavidula Ag. There are two kinds of fibro-cel bodies which 
_ Pervade the gelatiniform layer. One kind are irregular, dark, conspicuous cells, 
in appearance and size to those of the outer wall of the aboral side, with 
fink} 
