248 
I 
the dorsal side the secondary arm is considerably lower than the 
primary, which latter has the dorsal plates 3—4 irregularly divided. 
The comb of papillæ comprises both arms. 
The last case of forking arms in Ophiurids, which has come 
to my knowledge, 
is represented in 
textfigure 3. It is 
a specimen of Am- 
phiura Chiajei For- 
bes from the Sound, 
found by Mr. E. 
H. Stamm, who 
kindly placed it 
at my disposal. 
As seen by the 
figure the forking 
is near the end 
of the arm. Un- 
fortunately the arm has been somewhat twisted in the bifuicating 
region so that it would be necessary to cut it off in order to 
study the relation of the plates at the division point, but that did 
not seem desirable and I have preferred to keep the specimen 
intact. If it proves of importance to have the relation of the 
plates here made clear, it can always be done later on. 
Note. In my note “On natural hybrids of Echinoderms” x ) 
I have given as the only cases of natural hybrids in Asteroids 
recorded in literature Asterias berylinus X pallidus (from A. 
Agassiz) and Astei'ias groenlandica X hyperborea (from Kali- 
schewskij). I have there overlooked two cases, both much bettei 
*) Ecliinological Notes. III.—IV. Vid. Medd. Naturh. Foren. Bd. 63. 1911. 
p. 58—66. 
