245 
This interesting specimen was found in the Isefjord, Seeland, 
off Nykøbing, in the summer of 1904, by Mr. R. H. Stamm, who" 
kindly placed it at my disposal. The same monstrosity ocecurs in 
aå specimen, which I have found in the Limfjord in 1895. In this 
case the branching arm is nr. 4 to the right of the madreporite. 
The anatomical relations are as in the other specimen. The ad- 
ambulacral spines are normally disposed. 
Another interesting specimen of Asterias rubens I found in 
July 1900 in the Little Belt. Here one arm, nr. 3 to the right 
of the madreporite, is bifurcated. The ambulacral furrow is divided 
close to the mouth, so that from the oral side there appear to be 
6 arms; however, the inner pairs of tubefeet are only biseriate. 
On the aboral side the arm does not divide until at» a distance of 
a little more than 1 cm. from the disk. (The normal arm length 
of the specimen is 45 mm.). One coecum passes into each branch ; 
the genital organs -occupy the normal position at the base of the 
arm, not passing into the branches. 
Branching arms have previously been observed in Asterias 
rubens by Giebel!) and Giard?). As mentioned above, Verrill 
has found a similar case in Asterias epichlora. 1 may mention 
that I have seen a specimen of Asterias polaris M. Tr. in which 
one arm carries a small sidebranch near the tip. The abnormal 
arm is nr. 5 to the right of the madreporite (4. polaris is 6-rayed). 
The specimen being dried and rather badly preserved, no further 
information can be given. 
The specimen of Asterias Miilleri var. grånlandica Stp. figured 
PE IV, Pir; > presents another interesting abnormality. One 
arm, nr. 2 from the madreporite, has a double ambulacral furrow 
in its whole length; the space between the two furrows carries 
along the edges the adambulacral spines, apparently arranged bi- 
7) C. G. Giebel. Uber monstråse Seesterne. Zeitschr. f. d. ges. Natur- 
wiss. Bd. 20. 1862. p. 386. 
?) A. Giard, Sur certaines monstruosités de 1'Asteracanthion rubens. 
Compt. Rendus. T. 85. 1877. p. 973 
16" 
