REPORT ON THE ASTEROIDEA. 593 
I have added a new genus, Colpaster, for the reception of a form characterised by the 
presence of an externally conspicuous azygos interradial plate separating the first pair 
of adambulacral plates, and further differing from Freyella in the development of the 
armature of the mouth-plates and the adambulacral plates. 
Since the discovery of Brisinga endecacnemos in 1853, perhaps no other Asterid has 
been looked upon with so much interest by naturalists, or ‘has given rise to a greater 
amount of speculation as to its antiquity and structural relations. The Brisingide have 
been stated to represent the most primitive type of living starfishes, and to present a closer 
approach to the Ophiuroidea than any other form. I consider that these views are entirely 
unwarranted. It is now generally admitted by all workers at the group that the Brisin- 
gidee are most nearly related to the Asteriidz, Heliasterid, and Echinasteride. Taking 
Asterias as a comparatively well-known and central form, it may be asked, Does the plan 
of structure of this genus represent the most archaic or the most primitive type of Asterid 
structure with which we are acquainted? and, Does it present the nearest approach to. the 
plan of Ophiuroid structure? The reply to these questions would, I think, be unhesita- 
tingly in the negative. Supposing for the sake of argument that the Brisingide are older 
than the Asteriidee, May Asterias be considered to represent even a penultimate stage? I 
think not, and in my opinion such an assumption would be entirely without foundation. 
Paleontological evidence certainly does not support it, and the embryological history 
of Asterias points unequivocally to a phanerozonate ancestry. In my opinion the 
Brisingidee are true cryptozonate Asterids, very nearly related to the Asteriidz, Pedicell- 
asteride, Heliasteridee, and Echinasteride, and probably derived from a common ancestor, 
the divergence of form and the peculiarities of structure now exhibited by Brisinga being 
the result of modification produced by the extreme isolation and the exigencies of the 
abyssal depths in which the family has existed. We know too little of the embryology 
of Brisinga and its allies to speculate further at present on its antiquity or relations, 
and to say more than is suggested above in our present state of knowledge would be, in 
my opinion, to ignore altogether the evidence of palwontology and of the embryological 
development of those forms with which we are acquainted. 
Synopsis of the Genera included in the Family Bristnc1D&. 
A, Disk large. Rays very numerous. Abactinal plating reticulate. Forficiform 
and forcipiform pedicellarie present . 5 . : Labidiaster. 
B. Disk small. Rays not very numerous (six to seventeen in Sere oe) Abactinal 
plating when present not reticulate, No forficiform pedicellarie, forci- 
piform pedicellarize very numerous. 
a. Abactinal plating consisting of narrow widely-spaced transverse bands or 
ridges limited to the basal portion of the ray. 
a. Intermediate abactinal membrane punctured by papule 5 : Odinia. 
(ZOOL. CHALL, EXP.—PART LI.—1888,) 
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or 
