igo8.] Records of the Indian Museum. 23 



Specimen A has twenty pairs of lamellse, i.e., four vertical 

 series of ten. 



The lamellae, in the well-preserved specimen B, have a short, 

 sub-cylindrical, laterally- compressed stem ; but this is less obvious 

 in the other specimens, in which the branches come oft" at once as 

 flat leaflets. The lamellse are saddleshaped with the lateral edges 

 curving downwards ; accordingly, in the fragmentary specimen B, 

 it was possible to see at a glance which were the upper and lower 

 ends of the specimen. 



The lowest and oldest branches are reduced almost to mere 

 ridges. A fully formed lamella is 19 mm. long, and 18 mm. 

 wide. 



The single circular orifices on the upper and lower surfaces 

 are 4 mm. in diameter, and with well-defined slightly raised rim. 



The upper orifice, obliquely directed and pointing upwards and 

 outwards, is further awa}' from the central column than the lower, 

 which points downwards and outwards. In two instances there is 

 a third orifice near the upper edge, suggesting an atavistic return 

 to the form of colony with anastomosing tubes such as is found 

 in the less specialised species of Eiiretc. 



The orifices on the lower surface of the lamella persist to a 

 greater degree than those on the upper. Along one vertical series, 

 for instance, all the ten lower surface ones are open, but only the 

 four highest of the upper surface ones. In the orifices more recently 

 closed up it is still possible to see the outline below the thin layer 

 of dictyonal skeleton. 



Several of the lamellcC in B have a denticulate process or tongue 

 on the inner margin of the upper orifice and a larger one on the 

 outer margin of, or quite external to, the lower orifice. 



The lamellae are hollow at their origin, but l^eyond the ori- 

 fices the upper and lower laminae meet to form a thin edge. 



The Slieleton. — The dictyonal network does not present am- 

 striking peculiarities. The network has squaie or oblong meshes, 

 sometimes of considerable length, below the surface ; but at the 

 surface the meshes form polygonal areas, each polj^gon being divided 

 by spokes radiating from a centre, into triangular spaces. 



From the nodes arise spines var^dng in length, shape, thick- 

 ness and character of surface, but for the most part cylindrical, 

 knobbed and slightly tuberculated, and sufiicientty numerous to 

 give the surface of the sponge a hirsute appearance to the 

 naked eye. The spines round the lamellar orifices are verj' short 

 and terminate in spherical knobs. Among these spines are numer- 

 ous specimens of a Lituoline Foraminifer, which often so closely 

 resembles the spines, that it is not easy to distinguish them from 

 the latter. This organism is C3dindrical, with a bulbous base, and 

 with a surface layer of overlapping, fine, diamond-shaped, 

 vitreous plates. The resemblance between the skeletal spines and 

 the Foraminifer is so close as almost to suggest protective mimicry ; 

 though at the same time it is difficult to imagine how such a 

 minute organism could profit in this manner. 



