SYSTEMATIC ACCOUNT 241 



Stolon attached to the body. From the base it continues downwards as the free stolon, 

 which is 4-5 mm. long and ends in a knob. 



The proboscis is almost circular. It is of a pale brownish colour, but the edges are 

 dark brown like the dorsal side of the trunk. The ventral glandular wall of the proboscis 

 is not as thick as in C. hodgsoni or C. iiigrescetis, and this accords with the habit of 

 secreting a limited quantity of coenoecial substance. In the middle of the ventral wall 

 of the proboscis there is a thin short finger-like protuberance which is directed upwards. 

 Small sand grains might be held between this protuberance and the proboscis and thus 

 carried to the edge of the colony, to be there cemented on to the surface. 



There are usually eight pairs of arms which are conspicuous by their dark bands and 

 long pinnules. C. solidiis also has eight pairs of arms, but they are devoid of the black 

 pigmented bands which are seen only in C. nigrescens and this species. The pigmented 

 bands start from the base of the arm and run on each side. Near the tip they converge 

 and fuse into a single broad band. The tip has the appearance of a rounded knob without 

 pinnules. But this knob-like termination cannot be compared with the end-swellings 

 with refractive beads found in C. hodgsoni and C. dodecalophiis. The arms measure 

 1-2 mm. in length and the pinnules are 0-5 to o-6 mm. long. 



Though the zooids of C. solidus and C. ftimosiis are of the same size and possess the 

 same number of arms, the latter can always be distinguished by the presence of the dark 

 bands in the arms. The zooids of C. solidus are black in the preserved condition; thus 

 the colour of the preserved zooid of C.fumosus will also serve to separate the two species. 



Sub-genus Acoelothecia, sub-gen. nov. 



Diagnosis. Colony small or large, and branching ; formed of a meshwork of bars and 

 spines without any definite coenoecial cavities. Spaces between the meshwork irregular 

 and continuous and occupied in common by the zooids and their buds. 



Cephalodiscus kempi, n.sp. (PI. XXXIV, figs. 2-6). 



Diagnosis. Colony small and tuft-like or large and branching. The tuft-like colonies 

 are about 3-5 to 4-5 cm. from base to tip of spines. The branching forms sometimes 

 reach a length of 10 cm. and in thickest parts are 3-5 cm. across. The inhabited parts 

 of the colonies are formed of an elaborate meshwork of cross-bars between spines. The 

 coenoecium is devoid of definite tubes such as those found in the other three sub-genera, 

 whence the name Acoelothecia for the new sub-genus. Spines with varying length and 

 thickness are found all along the sides of the branches. No definite ostia are present. 

 Spaces between the surface meshwork of bars and spines act as temporary outlets. 

 Colour of the colony from light brown to reddish brown, older parts always of a deeper 

 tint. Length of a fairly extended zooid from base of body to tip of arms i-8 to 2 mm. ; 

 length from base of arms to base of body i-i mm. ; width of body 0-9 to i mm. Colour 

 of preserved zooids amber. Arms usually five pairs, with end-swellings and refractive 

 beads. Male, female and hermaphrodite zooids found in the same colony. 



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