LEUCAITDRA. 13 



wide as the body ; narrower in the oval specimens, it becomes relatively much 

 wider in the cylindrical ones. The body-wall is only 2-4 millim. thick, so 

 that the gastral cavity appears very roomy. The osculum is destitute of a frill. 

 Our sponge seems always to be solitary. The outer surface is covered by 

 dense spicules jn'otruding a good distance, and consequently makes the impres- 

 sion of a thick fur. The inner surface is slightly roughened. The canal-system 

 is different in different parts of the spouge : near the osculum it is extremely 

 simple, nolacunes or anastomoses of any kind are found there. The body-wall 

 is consequently very thin in this part (2 millim.). Further down towards the 

 aboral pole the gastral wall is perforated by large, densely scattered ronnd 

 holes, measuring 1*5 to 2*5 millim. in diameter. These exhalant pores lead into 

 longitudinal canals of an oval, transverse section, similar to those described in 

 a very different species, Leucandra meandrina, by myself. The apertures, or 

 rather short radial canals connecting the longitudinal tubes with the gastral 

 cavity, are conic or trumpet-shaped, wide at the mouth, they open with an 

 aperture not exceeding 0-5 millim. in diameter into the tubes. These longi- 

 tudinal tubes are clothed with the same skeleton as the stomach. 



S2ncides. — Gastral tetrad Sj)imles. Centripetal, sagittally differentiated 

 ray, straight, slender, and protruding into the tubes and gastral cavity ; 

 this ray is cylindrical and pointed, rarely slightly curved towards the end, 

 measuring 0-2-0-o5 x 0-01 millim. Three tangential rays equal, in a plane 

 vertical to the centripetal ray, straight, conic, and pointed, with equal angles 

 between them ; these rays measure 0*28 x 0-01 millim. — Triacts and tetracts 

 of the Parenchyma. Eegular triacts with straight, conic, and rounded rays, 

 measuring 0-35 x 0*02 millim., are predominant in the body-wall. Besides 

 these there are triacts of a similar size as the former, with curved rays and 

 more or less irregular angles. I have never met with proper sagittal 

 triacts. On these irregular spicules, and also on a few regular ones, 

 an incipient fourth ray can be observed. These forms lead up to tetracts 

 with conic, curved, and terminally rounded rays, measuring 0*3 x 0-018 

 millim., which are, however, rare. — The dermal diacts are of two kinds : 

 very slender linear spicules, and larger, but also slender and very long spindle- 

 shaped spicules. The latter are set at nearly right angles to the surface of 

 the sponge, and are very numerous ; they cause the hairy appearance of our 

 sponge. They are sharply pointed at both ends, and immersed about i-J of 

 their length in the body. They measure 2-3-5 x 0-035 millim. The shorter 

 ones are common, those measuring over 3 millim. in length found only excep- 

 tionally. The linear diacts measure 1 x 0-006 millim. 



Geographical Distribution. — East coast of Australia: Port Jackson 

 (Lendenfeld). 



