19 



eight or nine to the row, extending from the dorsal to the ventral median line. The basal 

 portion of the colony is almost bare of calyces. locm. from the base there are about 6 calyces 

 to the row, although almost the greatest diameter of the colony is here attained. 



The individual calyces are papillate projections directed distally, but with their adaxial 

 sides appressed to the stem and their mouths turned directly towards the stem, so that they 

 look like fleshy scales with flattened, semicircular free margins. They average about 2.2 mm. 

 long and .8 mm. in diameter. Their distal ends are often somewhat furrowed longitudinally, 

 but this is not constant. There are also often pronounced grooves which are vertical and 

 appear on the sides of the calyces. These are sometimes so pronounced as to give the margin 

 the appearance of being trilobed, the middle lobe being much the largest. The calyx opening 

 proper is entirely concealed in the preserved specimens by being turned directly toward the 

 stem, leaving merely a curved, slit-like opening between the outer calyx wall and the ccenen- 

 chyma of the stem. The inner or adaxial wall is very short and thin compared with the outer, 

 and is entirely covered by the latter. The polyps are very small, resembling those of Isis 

 hippuris. They are so strongly retracted and so difficult to separate from the mass of small 

 spicules of the fleshy calyx that is is exceedingly difficult to ascertain their characters. The 

 mass of retracted tentacles is bent at an angle with the basal part, the latter being at right 

 angles to the axis and the former inclined toward it. The polyp body has its walls thickly 

 strewn with small oval or lenticular spicules and clubs, the former being probably undeveloped 

 clubs, some of which extend to the dorsal surface of the tentacles. 



A section across the stem shows : 



1 . A layer of club-stars with their club ends directed towards, and forming the surface of 

 the colony. 



2. A very thick ccenenchyma filled with similar clubs in the outer portions intergrading with 

 symmetrical double heads and double stars in the inner parts. 



3. A series of small round openings of the primary water-vascular canals symmetrically disposed 

 a short distance outside of the axis. 



4. The axis cylinder, composed of a series of concentric lamellae of calcareous matter alter- 

 nating with horny layers within which is a practically solid core of calcareous matter. 



A longitudinal section shows that the polyps communicate with the water-vascular canals 

 by definite round openings rather regularly disposed in the walls of the canals. 



Spicules. These are all very minute and symmetrical. Those of the superficial layer 

 of the coenenchyma are club-stars, showing a distal clavate end truly club-shaped, covered with 

 thorny points directed distally. Below this spiny portion is a perfectly smooth shank of much 

 less diameter. The proximal end of the spicule shows a number of radiating points forming a 

 many-rayed star, or a head with numerous pointed rays symmetrically disposed on all sides. 

 They intergrade with the double stars or double heads which pack the inner portions of the 

 coenenchyma. These are beautifully symmetrical, minute spicules with a many-rayed head at 

 each end and a median perfectly smooth girdle. The outer spicules are yellow, while the 



