BY E. P. KALLMANN. 293 



question whether they belong to Spirastrella or Cliona; one may 

 mention, for example, Cliona phallica Leidy(25), and several 

 speeies described by Verrill(49), viz., Heter'oclioiiacribraria, Spira- 

 strella mollis, and apparently also Polymastia var'i.a. 



Having examined an undoubted example of Sph^astrell a fibrosa 

 Dendy(14), from the type-locality, I agree with Vosmaer that 

 this species does not belong to Spii^astreUa', I find it to be con- 

 generic with the species described by me(15) under the name 

 Latrunculia conulosa. 



Spirastrella australis. (PL XV., fig.o; PL xvii., fig.3). 



The species is well represented in the collection, botli by a 

 number of the original specimens and by others more recently 

 obtained; among the latter, there is a single small one which 

 diiFers from the rest in being of submassive form. The chief 

 distinguishing characters of the species are its typically com- 

 pressed plate-like form, its smooth and even surface without 

 tubercles or papilla?, and the density and compactness of its sub- 

 stance; in addition to these, but becoming manifest only when 

 the sponge has been macerated, is the reticulation of stout cord- 

 like " fibres " forming the main skeleton. An adequate idea of 

 the conformation of this skeleton may be obtained from the figure 

 (PL xvii., fig.3). Apart from being lamellar, the sponge is with- 

 out definite habit; occasional specimens are more or less regularly 

 flabelliform. Contrary to the description, apparently in no case 

 do oscula occur on either of the flattened surfaces of the sponge, 

 but only along its margin; and these are of minute size. Len- 

 denfeld's description of the canal-system, also, appears to me to 

 be quite without value. 



In thin sections cut transversely through the entire thickness 

 of the sponge, the naked eye can distinguish (i.)a less compact 

 middle region within which are denser areas corresponding to 

 transected "fibres," and, on either side of this, (ii.) a more com- 

 pact superficial layer of mottled appearance (because not uniformly 

 dense), which extends to the surface and has a width of 1-2 mm. 

 Under the microscope, the demarcation between these regions is 

 indistinct, and what difference there is, in their appearance. 



