634 THE VOYAGE OF H.M.S, CHALLENGER. 
margin. ‘The mouth-plates are small and inconspicuous, and each plate bears on its adoral 
margin two small mouth-spines, The inner pair are directed horizontally over the buccal 
membrane and are parallel to one another and the median interradial line ; the outer pair, 
which are at the outer extremity of the adoral margin of the plates, are likewise directed 
horizontally over the buccal membrane, but outward, forming an angle of about 45° to the 
inner mouth-spine. These marginal mouth-spines are less than 1 mm. in length, are 
covered with delicate membrane, and bear at the tip a number of small pedicellarize. Hach 
plate bears on its actinal surface a secondary or superficial mouth-spine, about 5 mm. in 
length, articulated on a prominent tubercle, and encased in a membranous sheath bearing 
large pedicellariz. 
The madreporiform body is small, convex, subtubercular, situated very near the abactinal 
margin of the disk; its surface 1s marked with but few, widely-spaced, striation-furrows. 
A distinct anal aperture is present, and its position is excentric. 
Colour in alcohol, a bleached yellowish ashy grey, with a slight tendency to a light 
brownish shade, especially on the ovarial regions. 
Locality. —Station 184. Off Torres Strait, Pacific side. August 29, 1874. Lat. 
12° 8’ 0” &, long. 145° 10’ 0” E. Depth 1400 fathoms. Globigerina ooze. Bottom 
temperature 36°°0 Fahr.; surface temperature 77°°5 Fahr. 
Remarks.—This species is nearly related to Freyella echinata, of which the echinulate 
forms might easily be considered at first sight as a variety. The general habit, however, 
of the two starfishes is different in many respects, notwithstanding their apparent nearness 
in several points of numerical formula, and when the unarmed forms are had in view there 
is very little in their superficial aspect that would recall Freyella echinata. In Freyella 
dimorpha the number of rays is twelve, and this appears to be fairly constant, whereas 
in Freyella echinata there are usually eleven. In Freyella dimorpha they are propor- 
tionately longer as well as more delicate and attenuate, whilst the ovarial regions are of 
less extent. The numerous small spinelets on the abactinal plated area are quite different 
from the armature of those plates in Freyella echinata. In Freyella dimorpha the lateral 
spines are considerably longer, although the species is relatively smaller, and their delicacy 
is exceptional. In this form the true or marginal mouth-spines are small, and their mem- 
branous investment as well as the grouping of the pedicellariz thereon is different. The 
saddle-hke sacculi upon the abactinal membrane of the ray beyond the ovarial region 
are broader and also maintain their breadth across the median abactinal keel. 
Although these differences may appear small in description, they represent variations 
of character which I find to be fairly constant in species, and on these grounds I have con- 
sidered the forms under notice as worthy of separate recognition. The dimorphous 
character of this species, some forms being echinulate and others not, is remarkable. The 
species also presents some resemblance, perhaps mimetic, to Freyella fragilissima and 
Freyella bracteata. 
