245 
specimen of Luidia sarsi Dib. Kor. taken on the same occasion 
has the two arms, nr. 3—4 to the right of the madreporite, coalesced 
at the base to about 0,5 cm. 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. 
The most interesting case of abnormalities in Asteroids, which 
I have found, is that shown in Pl. IV. Fig. 4. It is a specimen 
of Ceramaster (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 
arm, 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 Fig. 
1. Two paxillæ 
ones at the outer sides; in some places With pedicellariæ from 
the abnormal Ceram- 
aster granularis. %|1. 
there are two, irregular plates in the keel 
between the furrows. Most of the adambu- 
lacral 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 fact that a number of 
the paxillæ, especially those along the middle line of each arm 
Carry small pedicellariæ, each placed in a little deepening (Text- 
figure 1). In this species otherwise pedicellariæ do not occur; but 
in 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. japonicus (Sladen), C. patagonicus (Sladen), C. leptoce- 
ramus (Fisher). It may then perhaps not be unreasonable to see 
