44 THE VOYAGE OF H.M.S. CHALLENGER. 



whole, its internal organisation does not differ from that of the representatives of the 

 genus Spongelia, except in the size of the flagellated chambers. What Dr. Marshall 

 means by the words, "Das Gastrovascular-System ist hier nach dem astformigen Typus 

 ano-eordnet" {loc. cit, p. 113), is of course to be regarded as an echo of corresponding 

 erroneous statements of Prof. Haeckel. For any fine histological examinations the 

 Challeno-er specimen proved to be insufficiently preserved. The Alga found by Marshall 

 in all the specimens he had for examination was found to be characteristic also of the 

 single specimen collected by the Challenger. 



Colour. — Grey, skeletal fibres white. 



Habitat. — Station 162, April 2, 1874, off East Moncoeur Island, Bass Strait; depth 

 38 fathoms ; sand and shells. Dr. Marshall's specimens were also obtained from Bass 

 Strait. 



Psammoclema vosmaeri, n. sp. (PL III. figs. 5 and 6). 



This interesting species has been found in one colonial specimen, which is depicted of 

 natural size on PL III. fig. 5. Some individuals of the colony are mouthless, the oscula 

 of others are very small, and others again present cylindrical tubes, the diameter of the 

 oscula being thus the same as that of their body in its different parts. 



The surfaces of the sponge though entirely devoid of any conuli, are still rather 

 uneven and rough, but whether this is due to the state of preservation or is characteristic 

 of the species I cannot judge. The skeleton, when seen from the outer surface, admits 

 of no distinction into primary and secondary fibres, the network of the fibres being- 

 very compact, i.e., the meshes of a very small diameter, and it is only on the inner 

 surface that the vertically directed primary fibres, 0"16 mm. thick on an average, are easily 

 distinguishable ; most of the fibres, and particularly the larger ones, are charged with 

 foreign enclosures to such a degree that the enveloping horny substance is very thin 

 and the surface of such fibres very rough. When dried the skeleton becomes hard 

 and of a greyish colour. The type of the canal system and the histological structure 

 do not differ from those, for example, of SiMugelia pallescens, except that the flagellated 

 chambers are of smaller dimensions and comparatively more constant in their roundish 

 form, and that the internal cavity in some individuals is very large. Through the pores 

 of the outer surface the water reaches the system of inhalent canals, flagellated chambers 

 and exhalent lacunse opening by comparatively small holes into the internal cavity. 



From all other representatives of the genus hitherto known this species can be readily 

 distinguished both by its external shape, which is more like that of a calcareous than a 

 horny sponge, and by the compact network of its skeletal fibres, also perhaps by the 

 tendency to form colonies. 



I dedicate the species to Dr. G. C. J. Vosmaer of Naples. 



