6 



The Philippine Journal of Science 



1915 



Fig. 2. Spicules from the stem cortex of 

 Lithophytum rigiduni sp. nov. X 112.5. 



them divide in their distal por- 

 tion into two or three short, dis- 

 tally directed, main branches. 

 These branches divide to form 

 a number of lateral branches 

 and one terminal branch, which 

 bear the distally directed, single 

 or compound, polyp-bearing 

 catkins. In an expanded colony 

 the catkins are about 9 milli- 

 meters in length, and taper from 

 a basal diameter of 3.5 milli- 

 meters to a blunt point. 



The polyps which are tubular 

 or club-shaped are from 0.4 to 

 0.7 millimeter in diameter just 

 below the tentacles and from 

 0.5 to 0.8 millimeter in length. 

 When contracted, the tentacles 

 are folded in around the edge of the oral surface, leaving a 

 hollow in the center. When in a resting condition the tentacles 

 extend in the direction of the long axis of the polyp, and when 

 expanded they make a right angle with the long axis of the 

 polyp. The tentacles are short and broad and give the ex- 

 panded polyp a flowerlike appearance. There is a single row 

 of from 6 to 8 short, thick, rounded pinnules on each side of 

 each tentacle. The polyps arise close together on the catkins, 

 singly or in little clumps, or in broken oblique whorls. 



The endoderm of the entire colony from the base to the tips 

 of the pinnules contains many small unicellular algae, which 

 appear under the microscope as tiny transparent or greenish 

 spheres and which give the colony its peculiar greenish color in 

 life. 



The spicules of the stem cortex are straight or slightly curved 

 spindles covered with large somewhat irregular projections. 

 The spindles are from 0.15 to 0.4 millimeter in length and from 



Fig. 3. A spindle from the canal wall of Lithnphutum 

 rigidum sp. nov. X 47.3. 



