694 ' PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxv. 



are in one series, but much narrower than the body cavities shown in 

 the upper section. 



The leaf, then, below the polypiferous border, is divided into a great 

 number of quadrangular but narrow chambers, which are parallel to 

 each other and are separated from each other by septa which connect 

 the upper with the lo^Yer surfaces of the leaf. The chambers extend 

 from the body cavities of the polyps on the border of the leaf to a 

 semicircular canal yet to be described at the base of the leaf. There 

 is thus a chamber to each polyp, and a careful examination of the 

 sections of the leaf which cut across these chambers will show that 

 each of the four sides of the chamber bears the continuations of two 

 mesenteries, each septum between chambers bearing four, or two on 

 each side. As they approach the base of the leaf these chambers 

 become narrower until they are almost linear, and the regularity of 

 the arrangement of the mesenteries becomes deranged. But it is 

 still usually possible to detect eight mesenteries to each chamber. 



A section across a leaf of a sexually mature colony will reveal 

 numerous ova or spermaries, all of which seem to be attached to the 

 mesenteries which run down the sides of the partitions between the 

 chambers, as is shown in fig. 9, Plate LXXXV. 



The ova do not extend far below the bottoms of the oesophageal 

 tubes, however, and a section near the basal part of a leaf will be 

 devoid of them. 



At the extreme base of each leaf these chambers open into a com- 

 paratively large canal that is inside of the leaf where it joins the rachis, 

 and follows the curve of the line of junction of leaf and rachis for most 

 of its length, but finally plunges into the mass of spongy tissue under 

 the ventro-lateral aspect of the rachis and just beneath the mass of 

 zooids. This canal terminates blindly at its other end in the basal 

 portion of the leaf on the dorsal side of the rachis. 



Fig. 6, Plate LXXXV, shows a magnified view of the side of a leaf, 

 and the longitudinal markings made by the partitions between the 

 chambers are plainly seen. 



THE POLYPS. 



These are of the regular alcyonarian type, with 8 fringed tentacles. 

 They are white in color, and are expanded, in formalin specimens, 

 about 4 mm. above the calycular walls. The polyp mouth is usually 

 transverse to the polypiferous band of the leaf. Tentacles with 

 about 20 papillae on each side. 



The mesenteries show plainly through the translucent walls of the 

 polyps. Four of these bear ova and are disposed as described under 

 the head of "Calyces." 



There are no spicules, either in the tentacles or body walls of the 

 polyps. 



