264 



The following are tlie measurements of some of the more perfect 

 specimens : 



Length of Trunk Thickness of Trunk 

 1,75 cm 1,5 cm 



1,5 - 1 - 



2,2 - 0,8 - 



0,8 - 0,6 - 



All were attached to pieces of Madrepore coral probably Loplio- 

 helia sp. 



General Description. 

 The colony consists of 2 very distinct parts: (1) a bare trunk, and 

 (2) a polyp-bearing "pileus". The trunk is composed of a large number 

 of longitudinal canals with the adjacent walls fused and densely packed 

 with spicules, wdiich give consistency and rigidity to the colony. The 

 upper umbrella- shaped portion or "pileus" so closely resembles a 

 mushroom that the term "agariciform" might well be applied. The 

 general colour of the pileus portion of the colony is a pale orange- 

 yellow, while the trunk is whitish. The zooids, whose tentacles are not 

 retractile, are introversible within cylindrical stalks which are expanded 

 terminally into characteristic octagonal disc-like expansions. The close- 

 set octagons covering the pileus, with a zooid appearing in the centre of 

 each, present a most remarkable and unique appearance. 



The Canal System. 

 Fig. 2 represents a section through the trunk, and shows the out- 

 lines of the longitudinal canals, with their fused partition walls. Owing 



Fiff. 3. 



Fig. 2. a.-- 



Fig. 2. Section through the trunk showing the mesenterial filaments passing into the 



stem canals (x 8 . 

 Fig. 3. Enlarged section of one of these canals (x48>. a. ascular filament. 



to the contraction of the spirit-specimens, the mode of growth is by no 

 means obvious, but an examination of various stages, and of serial 



