1904.] SPOXGES OF THE GENUS LEUCOSOLEXIA. 363 



have. The straightness of the oscular tubes is rather a marked 

 featui-e of the '■^ pinus" form. Where Haeckel's figure is most in 

 error is in representing this tree-Hke form as an independent 

 growth arising by a massive trunk from a solid rock-foundation, 

 instead of being merely the upper part of a large colony. It is 

 these pinetree-like portions which generally drop off by their own 

 weight when the sponge is gathered, or become detached during 

 transport of the specimen, and it was doubtless to a fragment of 

 this kind that Haeckel's sense of artistic completeness supplied 

 the lacking foundation. I have also found L. com.plicata at 

 RoscoflT growing amongst the stems of algaj on rocks and isolated 

 boulders, in situations where it is left dry at the spring-tides, 

 though not at ordinary tides. Under these conditions also the 

 sponge shows the characteristic arborescent growth, but clings 

 close to the seaweeds and is never independent of them to any 

 great extent*. 



Comparing different specimens of this sponge, I find that the 

 most constant feature of its habit of growth is, that the erect and 

 often very long oscular tubes never grow to any length without- 

 throwing oiit diverticula, which, in their turn, gixe rise to other 

 diverticula and soon form oscula at their distal extremity. Hence 

 the oscular tubes of L. complicata are always beset with diverticula 

 to a greater or less extent, thus contrasting with the long, smooth, 

 usually slender oscular tubes characteristic of L. variabilis. The 

 body- wall is usually thinner and more delicate than in variabilis, 

 and the natural contour is a pure creamy white, except when 

 obscured by sediment and the numerous diatoms and other organ- 

 isms which settle on the exterior of the sponge. 



Another distinctive feature of this sponge is the shortness of 

 the oscular rim — that is to say, of that portion of the oscular tube 

 immediately surrounding the osculai- opening which is not lined 

 by collar-cells. 



(b) Characters of the Spiculation. 



(a) Triradiate and Quadriradiate Systems. — (1) The ordinary 

 triradiates, such as are found in every specimen (text-fig. 91, fig. 1 

 a-d, &c., p. 364), have the rays slender and tapering gradually to 

 sharp points. The unpaired ray is straight and distinctly longer than 

 the paired rays, oi' at least equal to them in length ; the exceptions 

 to this rule are so rare that they may be termed abnormalities. The 

 paired rays show a more or less distinct double curvature ; proxi- 

 mally they slope very slightly backwards for about two-thirds of 

 their length, while at their distal extremity they curve forwards 

 rather more sharply. The unpaired angle is only slightly greater 

 than 120°; so that the system often appears nearly equiangular, 

 but is never quite so. The usual length of the unpaired ray is 



* I am informed that Zostera-\ieA.s. similar to those at RoscofF occur also at 

 Jersey, and it is probable that from them come the specimens of this sponge sent 

 out 'hy Hornell's Zoological Station, and found in various collections with the label 

 Leucosolenia contorta. 



