BULLETIN OF THE 
Ophiomusium flabellum sp. nov. 
Plate V. Figs. 141-143. 
Special Marks. — Basal side arm-plates very flat and wide, encroaching 
much on the interbrachial space, and bearing stout spines on their outer edge. 
First under arm-plate similar to those beyond, and furnished with a tentacle- 
scale, First side arm-plates meeting on median line of lower interbrachial 
space, 
Description of an Individual. — Diameter of disk 3.3 mm. Length of 
arm 3.3 mm. Width of arm close to disk, without spines, 1 mm. Mouth- 
papille closely soldered together, forming a continuous line. Large triangular 
mouth-frames. Mouth-shields minute, diamond-shape. Side mouth-shields 
very large, meeting broadly within, with outer ends wide and much rounded, 
having a re-entering curve on the lateral edge, where stands the tentacle-sc: le. 
First, second, and third under arm-plates pentagonal, with a blunt angle within, 
outer edge slightly curved, and lateral sides re-enteringly curved ; the second is 
largest of the three ; the fourth and last is a minute, broad, triangular scale, 
without atentacle-pore. The first pair of side arm-plates are swollen, and of such 
extraordinary size as to meet on the median line of the interbrachial space ; the 
second are smaller, and meet above and below ; beyond the fourth under arm- 
plate they form the entire covering of the arm. Only two minute triangular 
upper arm-plates, having the outer edge slightly curved. Disk high and 
round, covered with thick, much swollen plates, whereof the middle are some- 
what sunken ; the central primary is pentagonal, surrounded by a row of angu- 
lar plates, of nearly equal size ; outside this row, in each interbrachial space, is 
another angular plate separating the inner ends of the rather long, closely 
joined radial shields. On the interb ‘achial margin is a large, much swollen 
boss, rising high above the other disk-plates, and connecting the neighboring 
radial shields. On the interbrachial space of the under surface there is but 
one minute triangular scale, outside the enormous first pair of side arm-plates ; 
these carry on their outer edge three small blunt spines, which look like mar- 
ginal disk-papille ; the next pair carry only two spines ; and beyond, there is 
only one, which is blunt and short, and carried low on the outer edye of the 
plate. Only three pairs of tentacle-pores (including the mouth-tentacles), cach 
with one large rounded scale on the, lateral sides of the under arm-plates. 
Color in alcohol, very pale brown. 
This species and O. pulchellum, by their large flat side arm-plates of the first 
pair, and peculiar first under arm-plate, which bears tentacle-scales, are strongly 
distinguished from others of the same genus. 
Off Port Jackson, 30 — 35 fathoms, 1 specimen. 
OPHIOPYRGUS gen. nov. 
Disk high and dome-shaped, covered with thick swollen plates, and sur- 
mounted by a central primary plate, which rises like a cone. Arms slender, 
