562 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. XXXIV. 
Genus CALIBELEMNON, new genus. 
Spicules almost or completely wanting; sarcosoma thick and fleshy ; 
polyps large, the general arrangement being in opposite pairs. 
Type.—Calibelemnon symmetricum. 
This genus shows the nearest approach to the next family, the Um- 
bellulide, of any known form, and forms a link of a chain of inter- 
gradation between the family Kophobelemnonidz and Umbellulide, 
the general shape of the colony allying it with the former, while the 
naked large polyps are apparently almost-identical with those of the 
latter. 
CALIBELEMNON SYMMETRICUM, new’ species. 
Plate XLII, figs. 1 and 2. 
Total length of colony 108 mm.; stem 50 mm.; rachis 55 mm. Stem 
fleshy, rather distinct end-bulb, and a fleshy swelling reaching the 
greater part of the distance to beginning of rachis. Rachis more 
slender, the axis reaching through its entire length, as well as through 
the entire stem, and projecting as a point beyond the distal pair of 
polyps. | 
Polyps in pairs, projecting from ventral side of rachis, but em- 
planted laterally; in general they are arranged in groups of two 
pairs; of which the upper is smaller and apparently younger than 
the lower, and is inserted more ventrally than the latter This 
arrangement, although common, is not constant. There 1s often a 
regular increase in size from the lowest to the distal polyps, the low- 
est being but 2 mm. in height, and the distal being 11 mm, to the 
base of the tentacles. The colony is often terminated by three polyps 
in a cluster, one being between the distal pair and having behind it 
the sharp distal end of the axis. 
The individual polyps have a swollen basal portion in which the 
ova are seen and which is 2 to 3 mm. high; the remaining portion 
of the body being longitudinally ribbed by the mesenteries showing 
through as whitish bands relieved strongly by the purplish brown 
of the intervening polyp walls, and transversely corrugated by nu- 
merous fine muscle bands. The tentacles themselves are very long, 
filamentous and nonretractile. The entire polyp is almost exactly | 
hke a small Umbellula polyp. 
Zooids.—Both the ventral and dorsal sides of the rachis have a 
median well-defined longitudinal band which is entirely devoid of 
zooids, so that it is impracticable to decide which is dorsal and which 
ventral, although, judging from certain species of Umbellula, the 
side with the free end of the rachis is ventral. The zooids are 
crowded in great numbers over the entire surface of the rachis, with 
the exception of the bands above referred to. 
