156 PERCY SLADEN TEUST EXPEDITION. 



resembling those of the verruca, more or less rectangular in outline, and 05-0'9 mm. 

 long. All these large scales are closely covered with minute conical tubercles. 



Besides these spicules there are many typical " Blattkeulen," 0"3x0'19, 0'5x0'28, 

 with tuberculated heads. These merge into irregular plates resembling flattened-out 

 " Blattkeulen," and measuring about 0'5x0'5 mm. 



Variously shaped tuberculated spindles also occur, 03 X 017, 0-2X0-16, 0-24. XQ-l. 



Locality. Saya de Malha (C 1), 150 fms. 



34. Acis alternaiis, sp. n. 



A white colony with a strong main stem, 76 mm. in height, from which branches 

 arise alternately, and spread in one plane to a maximum breadth of 50 mm. The 

 verrucas arise on the sides of the stem and branches, but are markedly turned to one 

 surface. They occur more or less alternately, and there is occasionally one on the face 

 of the axis. They are truncated cones, about l"5-2 mm. in height by 2 mm. at the base, 

 and there are six to eight in a centimetre. All the spicules, both of the ccenenchyma and 

 the verrucse, are warty spindles ; those of the verructe lie for the most part vertically, 

 and often form eight projecting teeth ; the general surface is rough and the spiadles 

 overlap, not being neatly fitted into one another as in many other species. There is a 

 prominent operculum of eight triangular points, each consisting of two converging 

 spindles and two horizontals, one below the other, at the base of the triangle. The 

 following measurements were taken of length and breadth in millimetres :— 



[a) General spicules: 38 X 0-67, 27 X 0-44., 2-6 X 0-49, 12 X 0-28. 

 {b) Polyp-spicules : 0-7 X 021, 058 X 0-12. 



This form has a considerable resemblance to the figure of A. pustulata given by 

 Wright and Studer, and there is great similarity in the general spiculation. But in 

 A. pustulata the verrucse are much smaller and closer; the spindles form a much 

 smoother pavement, and there is an interlocking by marginal denticulations ; and the 

 operculum is described as violet. A comparison with the ' Challenger ' specimen of 

 A. pustulata showed the marked difference between it and this new species, which is, 

 however, apparently nearer to it than to any other. 



Locality. Salomon, 60-120 fms. 



35. Acis obscura, sp. n. 



That this species is not a typical Acis is evident at once from its spiudle-shaped 

 spicules. It resembles an Acis, however, in general appearance, and it will fit into no 

 other genus. It seems better to include it in Acis, for it seems to be an Acis in the 

 maldng. 



The colony is of a somewhat thick and clumsy build, and branches rather sparingly in 

 a more or less dichotomous fashion, in one plane. The colony is 16 cm. high and 10 cm. 

 broad. The axis is throughout very thick, being 4 mm. in diameter at the base and 

 2-3 mm. in the branches. It is dark brown in colour, and finely and irregularly grooved. 



