LANUG INELLA PUPA. 7 



tho dermal membrano. Seen under the hand-lens, the dehcate 

 dermal lattice^York contains minute meshes whicli are more or 

 less regularly rectangular in shape, though in certain individuals 

 I have found tliem irregularly shaped throughout nearly the entire 

 extent of the layer. With the larger-meshed hypodermal lattice, 

 it is quite usual that the intersecting of the thin laths takes place 

 in an irreo'ular manner ; only seldom are the meshes of a rectan- 

 gular shape. Generally speaking, the ectosomal skeleton seems to 

 lie in tolerably close apposition to the choanosomal mass, so that 

 the subdermal space is but inconspicuously developed. The en- 

 trances into incurrent canals, indistinctly visible from the outside, 

 are small ; the larger of them are separated from one another by 

 a comparatively wide interspace. 



Towards the stalk-like base of the sponge the hypodermal 

 lattice becomes unnoticeable. It is here rejilaced by parenchymal 

 bundles running in the main longitudinally and with these the 

 ectosomal layer is apparently in direct contact. 



The gastral cavity, instead of being lined with a continuous 

 gastral or endosomal layer, shows the apertures of excurrent canals 

 freely open. Many of the apertures are much larger than those 

 of the incurrent canals in the same specimen. They may measure 

 2mm. across in fully grown specimens. 



Spiculation.-' 



Tho parcnchyrnaUa consist of oxyhexactins and oxydiactins. 

 In both these forms the rays run out to a sharp point and are 

 either smooth all over or show a roughness near the end. 



* I am intiebtcd to I'roiessor F. E. ScnULZK for a slide-preparation of Lanuginella pupa, 

 — presnma})iy of oiip from tiio Oliallonger enlloetiDii. Tt lins heen useful fir the piir[)o«e of 

 comparison. 



