124 PROF. BELL ON NEW SPECIES OF ASTEROIDEA. ([Jan. 17, 
actinic peculiarity ; and the decision can only be given with the aid of 
evidence which proves or disproves the idea that the species can and 
does undergo division. Such evidence is here afforded by the spe- 
cimen in the national collection; for it has the arms of different 
lengths ; this, of course, points to some of the arms being younger 
than the others, or, in other words, as having arisen by gemmation 
after division. 
The heteractinic, rather than the sexradiate, condition should 
therefore be regarded as a part of the diagnosis of the species. 
FRomiA TuMIDA, n. sp. (Plate VI. figs. 4, 4a.) 
Arms and disk more swollen than in most of the species of the 
genus. R=45,r= 14; R= 35, r= 11'5,orR=3°2r (about) ; 
breadth of arms at base 14°5, 12°5 millim. All the plates on the 
actinal surface, with the exception of those of the marginal series, are 
closely covered with stout spines, from which the spines of the adam- 
bulacral series are distinguished by their smaller size. The whole of 
the abactinal surface is covered by squarish-headed granules, which are 
all of very much the same size, and are all very regularly distributed ; 
they are arranged in elliptical aggregations, two or three rows of 
which extend along the back of the ray, or they are placed between 
these aggregations ; in the former case they are somewhat more 
closely packed. The intermediate spaces, in addition to the 
granules, present a certain number of pores, which, however, are, 
in comparison with other species of this genus, rare. The madre- 
poric plate is rather nearer the margin than the centre of the disk, 
and is very similar to the same body in F. milleporella. There are 
about seventeen marginal plates in both the actinal and abactinal 
series ; and both sets are covered with granules of a fair size ; and the 
marginal granules of each set are to be easily distinguished from the 
more central ones which they surround. For some way along the 
surface of the arm the dorso-marginal plates are deeper than long ; 
the infero-marginal plates are much more nearly square. There 
seems to be a large pore at the proximal angle between the two sets 
of marginal plates; but as the two specimens on which this deserip- 
tion is drawn up have both been dried, it is not possible to speak 
definitely on the point. The same remark will apply to the pore at 
the proximal angle of the actinal edge of the infero-marginal plates. 
The adambulacral spines appear to be arranged in three longi- 
tudinal rows. They are subequal in size, and diminish very slightly 
as they approach the free end of the ray. The space between these 
spines and the marginal plates is completely occupied with short 
stout spines, set in tufts on small plates. No pedicellarie. 
Ceylon. Presented by M. Kelaart. 
EXPLANATION OF PLATE VI. 
Fig. 1. Scales of Calvasterias antipodum, X 4:1. 
2. Abactinal surface of Cribrella minuta, X 2:1. 
3, 3a. Actinal and abactinal surfaces of Mithrodia victorie, x 2:1. 
4,4a. Actinal and abactinal surfaces of Fromia twmida, showing the 
arrangement of the plates and spines, X 3: 2. 
4b, Portion of actinal surface, more highly magnified. 
