ARTlcr.E XXIV. -TWO SPONGES FROM CAMPBELL ISLAND. 



By H. B. Kirk, M.A., Professor of Biology, Victoria College, Wellington. 



PLATE XXV. 



Leucosolenia, Bowerbank, 1862. 

 Leucosolenia echinata. 



Leucosolenia echinata, Kirk, Trans. N.Z. Inst., xxvi, 177. 



This sponge was found between the tide-marks in Perseverance Harbour, 

 Campbell Island. The sponge has not been reported outside 'New Zealand. 



Stylohalina, n. gen. 

 Halichondrine sponges, in which the skeleton consists entirely of styli. 



Stylohalina conica, n. sp. (Plate XXV.) 



Sponge forming flattened or conical masses, each cone having at its apex a 

 single large oscule. The surface of the sponge shows numerous minute elevations, 

 between which lie definite pore-areas, irregular in outline. In each area there are 

 from 5 to 20, or more, small round or oval pores. At times several pore-areas are 

 confluent. The dermal membrane is glossy, and of close texture, but quite thin. 

 The surface is echinated by projecting spicules. Diameter of one of the two speci- 

 mens, 2-5 cm. ; height from base of sponge to summit of oscule-bearing cone, 1 cm. 

 The other specimen has a diameter of 4 cm., and is less regular in shape. Colour, 

 yellowish-white. 



Skeleton entirely of styli (flgs. 2, 3). The basal end of the spicule is usually 

 evenly rounded, and from this end for about two -thirds of the length of the spicule 

 there is little or no tapering ; then the spicule tapers slightly, and presently more 

 noticeably, terminating in a sharp point. Occasionally there is a slight approach 

 to the tylostylote condition, a slight swelling developing close to the base. This 

 swelling does not always extend right round the spicule, but sometimes suggests a 

 short, blunt, feebly developed spinule. All, or nearly all, the spicules are very 

 slightly curved, and usually, near the apex, there is a still slighter curve in the 

 opposite direction. Thus the curvature of the spicule is, on the whole, slightly 

 sigmoid. Average size of spicules 0-36 mm. by 0-01 mm. 



In the dermal membrane the spicules are numerous on the papillae, where 

 many spicules have the apical portion projecting at almost any angle. A few 

 spicules lie parallel to the surface. In the pore-areas there are fewer spicules, the 

 membrane being very thin. In the body of the sponge spicules are not numerous, 

 and are usually scattered irregularly ; sometimes arranged in small irregular groups. 



