REPORT ON THE ASTEROIDEA, 5 
Genital foramina opening upon the abactinal surface close to the marginal plates on 
each side of the odd interradial plate. 
Remarks.—The genus Benthopecten, recently described by Verrill,) is stated to be fur- 
nished with abactinal plates covered with skin, usually bearing a single spine or sometimes two 
or three, but not forming true paxille. This character would seem to indicate an alliance 
with Pararchaster ; but from the brevity of the description I cannot say whether this be 
near or remote, and I am for the same reason unable to indicate in the foregoing synoptic 
table the relative position of the genus in the family. No mention is made of the presence 
of any odd interbrachial marginal plate and spine, or of the limitation of the papule to 
the basal region of the rays,—characters which are so conspicuous in Pararchaster, and 
whose importance from a structural point of view could scarcely have been overlooked by a 
naturalist so well acquainted with starfish anatomy as Professor Verrill, had they been 
present in Benthopecten. Furthermore, no mention is made of the presence of any pedi- 
cellarian apparatus. On the other hand it is recorded that “a circle of four to six papille, 
placed singly, surrounds each plate.” If the word “papillee” here stands for the organs 
which I call papule (following Stimpson), it would appear extremely doubtful whether 
Benthopecten would find a place even in the same subfamily as Pararchaster. 
The subjoined scheme will assist in the ready recognition of the different species of the 
genus. 
Synopsis of the Species included in the Genus Pararchaster herein described. 
A. No pedicellariz of any kind. Single spinelets on the abactinal plates. 
a, Abactinal area of disk plane. One supero-marginal spine. Adambulacral 
plates with two actinal ae No line of thornlets on the infero-mar- 
ginal plates ‘ : j . : : 5 semisquamatus. 
b. Abactinal area of disk inflated. T wo supero- praieaall spines. Adambulacral 
plates with three actinal spines. <A line of thornlets on the infero-mar- 
ginal plates : : antarcticus, 
B. With special comb-formed pedicellarize, Abactinal plates with one to three or 
more spinelets. 
a, With pedicellariz between each infero-marginal plate. e : “ pedicifer. 
b. With no pedicellariz between the infero-marginal plates. 
a. One lateral spine on infero-marginal plates and a small companion. 
Adambulacral plates with six or seven furrow spines, one 
actinal and sometimes a small companion behind it. Abac- 
tinal plates with one or two spinelets, all simple. Comb-like 
pedicellariz on the abactinal surface : : : armatus. 
b. Three or four lateral spines on infero-marginal pees Adambulacral 
plates with four furrow spines, and two actinal side by side, 
Abactinal plates with several long needle-like spinelets inter- 
spersed amongst the simple ones. No comb-formed pedicel- 
lari on the abactinal surface . : : c c : : spinosissimus. 
1 Amer. Journ. Sct. and Arts, Sept. 1884, vol. xxviii. p. 218. 
