221 



0-4 X 0-3 folia Ol> long. 



0-35 X 0-35 „ 018 „ 

 0-3 xO-15 „ 0-2 

 0'35 X 0-3 „ 0-2 

 The spicules of the authoeodiie are spiny spindles and measure in milli- 

 metres, 0-3 X 004 ; 0-3 x UOG ; 02 x 003 ; 01 x 002. 

 Locality : Arakan Sea, 13 fathoms. 



GENUS MENACELLA, Gray. 



This genus was founded by Gray for Goiyoiiia retinilmii, Pallas (" Ann. Mag. 

 Nat. Hist.," Ser. 4, vol. v. p. 406), but Ridley ("Ann. Mag. Nat. Hist.,"Ser. 5, vol. 

 ix. ) points out that Gray's species does not agree with that established by Pallas, 

 so that it must be termed Menacella reticularis, Gray, nee reticulum, Pallas. 

 Gray's diagnosis is as follows : " Coral very much branched, fan-shaped, 

 irregularly reticulated ; stem simple. Bark very thin formed of numerous 

 very slender fusiform spicules in bundles placed in different directions. Polyp 

 cells short, cylindrical, covered with spicules like the bark, with a smooth, 

 convex eight-rayed lid, placed close together on the sides of the branchlets and 

 more scattered and further apart on the sides of the branches." To this 

 Ridley adds : " In its spiculation it differs very decidedly from the members of 

 the genus Villoi/on/iu, in having none but simple tuberculate fusiform spicules, 

 with strongly micro-tuberculate or exfoliating tubercules ; the spicules are 

 black in colour with the exception of the tubercules which are colourless ; the 

 largest measure 0:5 x O'lOl mm." 



In the present collection there is a colony which comes nearest to this 

 genus but differs from it in certain particulars. 



Menacella gracilis, n. sp. 

 Plate VIII. tig. 16 ; Plate VI. fig. 0. 



A large colony 115 mm. in height and 80 mm. in maximum lireadth, 

 branched in one plane and of a creamy- white colour. The branches arise almost 

 perpendicularly and diverge only slightly from their original direction. The 

 main stem extends to the very top of the colony and tapers markedly from 

 2-25 mm. at the base to an almost thread-like fineness. There is no anasto- 

 mosis. The axis is horny and soft, very flexible in its upper half. It is dark 

 in colour in the older portions but gradually changes to pale yellow in the 

 twigs. 



The coenenchyma is very thin and allows the dark axis to shine through in 

 the lower parts. The spicules are arranged longitudinally and this disposition 

 is continued up the sides of the verruca?. Many cirripede galls occur and these 



