257 



(a) Outer layer of ccienenchyma, 35 x 0275 ; '25 x 025 ; 2 x 0-2. 



{/)) Inner „ „ 035 x 0075 ; 03 x 005 ; 0-2 x 0-05. 



(c) Verrucc>?, 1 x 0175 ; 0-8 x 0-15. 



{d) Tentacles, 0175 x 0025 ; 015 x 0-02. 



This new species is quite distinct from other species of Mnrlcdla in — 



(1) The mode of branching. 



(2) The architecture of the verrucse. 



(3) The nature of the operculum. 



(4) The size and shape of the large outer spicules. 

 Locality: Arakan Coast, 13 fathoms. 



Muricella robusta, n. sp. 

 Plate V. fig. 8. 



Two small colonies of a dusky brown colour, which differ from the usual 

 type of MuHcella species, seem to be new. The larger is 80 mm. in height and 

 30 mm. in maximum breadth, and consists of a long main stem from which 

 three lateral branches arise. The smaller is 25 mm. in height and 50 mm. in 

 breadth ; the central main stem gives origin to five lateral branches and these 

 in turn bear smaller twigs. Both specimens are characterised by their 

 robustness. 



The axis is cylindrical, horny, soft and flexible. It is of a brownish colour. 



The coenenchyma is very thick ; in the younger portions it is thicker than 

 the diameter of the axis. There are two distinct layers of spicules, an inner 

 layer of very numerous small red spindles, and an outer of larger semi-trans- 

 parent short and thick warty spindles. The latter are very uniform in size, 

 closely packed but with no definite arrangement. The coenenchyma is very 

 rugose and does not show the interlocking of spicules such as is characteristic 

 of, e.g., M. nihra. The exterior recalls the appearance of a spiculose Siphono- 

 gorgid. 



The polyps display a tendency to a bilateral arrangement, but this is often 



broken through so that they appear to occur all round. The verructe are large 



and conical ; they are about 2 mm. in diameter at the base and over 1 mm. in 



height. The spicules are arranged longitudinally in eight sheaves which pass 



by gradual transitions into the coenenchymal amature. The anthocodife are 



completely retractile, but in many cases the verruciie are contracted so that the 



polyp appears dome-like on the top. On the aboral surface of the tentacles there 



is a dense amature of spicules which is very characteristic. Below this there 



is a distinct crown and point arrangement. The crown consists of three to four 



rows of curved spindles, and each point is made up of at least three pairs of bent 



spindles arranged " en chevron " ; in many cases there are more. When the polyps 

 33 



