245 
specimen of Lutdia sarsi Dub. Kor. taken ou the same occasion 
has the two- arms, nr. 3-4 to the right of the madreporite, coalesced 
at the base to about 0,5 om. distance form the disk. The inner 
anatomy of these coalesced arms rather unexpectedly shows them 
to be like one branching arm; there is only one coecum in each 
arm, and the genital organs are developed only along the outer 
side of each arm. 
Ihe most interesting case of abnormalities in Asteroids, which 
I have found, is that shown in PI. IV. Pig. 4. It is a specimen 
of Cer amaster (Pentagonaster) granularis 
(Retz.), which I found in 1911 in Trond- 
hjemfjord, in a dredging off the little is- 
land Tautra, in a depth of ca. 200 m. One 
aim, nr. 3 to the right of the madreporite, 
is considerably longer than the others and 
has its ambulacral furrow divided from the 
middle of the arm, the outer part having 
two parallel ambulacral furrows, separated 
by a keel formed by a row of adambulacral 
plates, somewhat broader than the normal 
ones at the outer sides; in some places 
there are two, irregular plates in the keel 
between the furrows. Most of the adambu- 
Fig. 1. Two paxillæ 
with pedicellariæ from 
the abnormal Cerum¬ 
aster granularis. 30 h. 
laeral spines on this abnormal part of the arm were abraded, but 
it appears that they did not differ in their arrangement from those 
along the normal furrows. - More interest, however, is afforded 
by the dorsal side of the disk through the faet that a nnmber of 
the paxillæ, especially those along the middle line of each arm 
carry small pedicellariæ, each placed in a little deepening (Text- 
figuie 1). In this species otherwise pedicellariæ do not oecur; bnt 
m other species of the genus a similar form of pedicellariæ occurs 
in the dorsal paxillæ '(besides other pedicellariæ on the oral side), 
e. g. in C. japomeus (Sladen), C. patagonicus (Sladen), C. leptoce- 
ramus (Fisher). It may then perhaps not be unreasonable to see 
