562 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxiv. 



Genus CALIBELEMNON, ne\v genus. 



Spicules almost or completely wanting ; sarcosoma thick and fleshy ; 

 polyps large, the general arrangement being in opposite pairs. 



Type. — Galibelemnon symmetricum. 



This genus shows the nearest approach to the next family, the Um- 

 bellulidge, of any known form, and forms a link of a chain of inter- 

 gradation between the family Kophobelemnonidse and Umbellulidae, 

 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 

 l^olyps. 



Polyps in pairs, projecting from ventral side of rachis, but em- 

 j)lanted 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 is 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 Avhitish 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 

 like a small Umhellida 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 Vmhellula., the 

 side with the free end of the rachis is ventral. The zooids are 

 crowded in great numbers over ftie entire surface of the rachis, with 

 the exception of the bands above referred to. 



