52 Records of the Indian Museum. [Vol. VI, 



Racodiscula sceptrcUifera (Carter). 



Discodermia sceptrellifera, Carter, Ann. Mag. Nat. Hist. (5), vol. 



vii. p. 372, pi. xviii, fig. 2 (1881). 

 Racodiscula sceptrellifera, von Lendenjeld , Das Tierreich^ Lief. 19 



(Tetraxonia) . p. 132 (1903). 



Carter's description of this species was based on a specimen 

 *' not only small but imperfectly developed " and partiall}- embed- 

 ded in a nodule of the calcareous alga Melobesia. It is therefore 

 unfortunate that the form he described must be regarded as the 

 forma typica of the species. Among the specimens obtained by 

 the " Golden Crown" two other forms may be distinguished, each 

 associated in several or many instances with a particular species 

 of Siliquaria or Spiroglyphus. Possibly they are mere phases, 

 their peculiarities being due to the direct effects of environment, 

 but it will be convenient to regard them provisionally as varieties 

 of Carter's species, with which I have no doubt the}^ should be 

 associated. 



Var. spiroglyphi, nov. 



(Plate viii, fig. 2 ; plate ix, figs, i — 15.) 



Sponge of a deep orange or bright red colour when fresh, 

 yellow when dry, coating and filling the interstices between shells 

 of Spiroglyphus cummingi (Morch), often massive, but without 

 definite form, verj^ hard ; the surface smooth, with scattered os- 

 cula of oval form and varying from 2 X 2"5 mm. to 3 X 4 mm. in 

 dried specimens; pores sieve-like, scattered, minute, each aperture 

 measuring about 0*33 X 0*5 mm. The main efferent channels run 

 as a rule obliquely. The surface of the sponge, immediately under 

 the dermal layer, is scored with narrow channels which enter the 

 efferent canals close to the oscula. The lining of the latter is a 

 coUenchyma which is sometimes as much as 3 mm. thick and con- 

 sists of numerous nuclei embedded without visible cell-limits in a 

 gelatinous substance. This substance is not destro3'ed even b}^ 

 hot nitric acid, at any rate without prolonged boiling. Slender 

 fibres can be detected in parts of the coUenchyma, running verti- 

 cally. (My material is not sufficiently well preserved to render a 

 detailed description of the soft parts possible.) 



Skeleton and Spicules. — The skeleton consists of stout desmas 

 (pi. ix, figs. 8 — 14) of the typical form firmly welded together by 

 means of the proliferations at the ends of the branches. The 

 shafts are smooth or nearl}^ so. Where the sponge is in contact 

 with the shells with which it is associated the tips are flattened 

 and splayed out in a horizontal plane. Towards the external part 

 of the sponge, where growth is evidently most active, many of the 

 desmas afford a transition, more apparent than real , to the phyllot- 

 riaene dermal spicules (pi. ix, figs. 8,9; see also Carter, op. cit., 

 pi. xviii, fig. 2e). Their shafts are more slender, their terminal 

 proliferations less developed than in other desmas, and often 



