247 
in the middle line of an interradium. Studer is of opinion that 
»der Ursprung eines neuen Armes "Zwischen zwei normalen deutet 
wahrscheinlich die Einleitung zu einem Selbstheilungsprocesse an". 
I do not think that suggestion very probable. In other self- 
dividing Ophiurids the division is not preceded by the formation of 
one or more new arms between the old. The case of Ophioscolex 
prolifer evidently | 
only represents a 
monstrosity, not a 
usual instance of 
meristic variation. 
Å specimen of 
Ophiura  (Ophio- 
Jlypha)  albida 
Forbes, which I 
have dredged at 
Herthas Flak in 
the northern Kat- 
tegat ("Ragna” 
1905) has one 
arm — bifurcating 
FE IV. Fig. 6) 
Ås seen from the 
analysis given in 
textfigure 2 the 
. Textfigure 2. The inner joints of a bifurcating 
Point of division arm of Oph. albida. I. 
is about at the 
hird joint. The second ventral plate is abnormally formed, the 
third is divided by a longitudinal line. The fourth ventral plate 
of the main arm is divided into four small plates; between the 
ventral plates 3 and 4 are seen two pentagonal plates, the inner 
of which evidently represents the one side plate of the third joint, 
while the interpretation of the other remains uncertain. From the 
fourth joint both arms have normally shaped plates. Seen from 
