1 'i 



LEUCANDRA. ^^ 



shape of an irregular cone or spindle, or may be ovate. The osculum is always 

 situated terminally on the narrow end of the cone. 



Leucandra vaginata attains a height of 30-40 millim., and a diameter of 

 12-20 millim. The body-wall is thick, particularly in the short and irregular 

 specimens, the gastral " cavity measuring only H of the diameter of the 

 sponge. The osculum is sometimes surrounded by a frill. The canal-system 

 is rather complicated ; the inhalant pores lead into a reticulation of tangential 

 canals below v,he surface, all of which possess a circular transverse section 

 and a diameter of 0-2 millim. The meshes of this reticulation are wide, so 

 that no lacunes, which might be regraded as subdermal cavities, are formed. 

 Towards the gastral wall we meet with irregular, circular canals extending 

 tangentially, but not regularly longitudinally. I am doubtful as to whether 

 these form a reticulation ; I think not. If anastomoses are present they are 

 very rare. From these canals numerous small radial tubes, only 0-2 millim. in 

 diameter, lead into the gastral cavity. The terminations of these, the pores 

 in the gastral wall, are of the same dimensions as the canals to which they 

 belong, and very close together. 



Spicules.— The skeleton consists of similar elements as that of the foregoing 

 species. Gasiral tetrads. Centripetal, protruding ray 0-1 x 0-008 millim., 

 conic, pointed, mostly straight, sometimes slightly curved near the end. 

 Tangential ray sagittally developed ; one ray situated longitudinally and point- 

 ing towards the aboral pole, shorter than the other two ; angles on the sides 

 of it equal, about 100° ; this ray measures 0-08 x 0-006 millim., the other 

 two equal' rays 0-12x0-008 millim.— Tmci and tetmct spicules of the 

 Parenchyma. The triacts are equiangular, with straight, conic, terminally 

 rounded rays, the rays mostly sagittally developed; the unpaired ray 

 longer than the other two, pointing outward, and measuring 0-28x0-014 

 millim., the others 0-22x0-014 millim. Some regular triacts are also met 

 with ; their rays have varying intermediate dimensions between the longer 

 and 'shorter ones of the sagittal triacts ; some of the latter show an 

 incipient fourth ray. Decidedly tetract spicules are rare ; their rays have 

 the same dimensions as those of the triacts, but are generally curved.— 

 Diact Spicules. These measure 0-7x0-035 millim., are spindle-shaped and 

 slightly curved, the concave side towards the osculum. They are immersed 

 in the body of the sponge about half their length, and stand nearly vertical to 

 its surface; both ends are sharply pointed. These spicules are not very 

 numerous. The sheath, which covers the spicules of calcareous sponges 

 generally, is very highly developed on the protruding part of these spicules, 

 much'more so than in any other calcareous sponge known to me ; and I have 

 derived the specific name from this characteristic peculiarity. 



Geographical Distribution.— East coast of Australia: Port Jackson 

 (^Lendenfeld). 



