51 



The liypogastral hexactines are on the whole similar to those of H. rohustus. 

 The hypodermal hexactines differ from the corresponding spicules of that species 

 however by the greater length of their inner, gastral, radial ray, which is 2 mm. 

 long. Also this difference is correlated with the absence of parenchymal 

 hexactine supporting spicules. 



The root-tuft is in great part composed of the lower longitudinal rays of 

 principal pentactines. Its anchor-spicules agree with those of H. rohustus. 



Of the intermediary parenchymalia of H. rohustus the stout micro-oxyhex- 

 actines and the oxyhexasters they pass into, are absent. The slender oxyhex- 

 asters are, on the other hand, present in much greater numbers than in K. rohustus. 

 These differ from the corresponding spicules of the latter only in the curvature 

 of the branch-rays which are nearly straight and not nearly so strongly bent as 

 in H. rohustus. 



Graphiocoms are not numerous and are irregularly scattered through the 

 dermal region. I have seen several intact ones with dermal brushes of branch- 

 rays 200 A* long in situ, still attached to the main-rays. 



In the subdermal and particularly in the subgastral region irregularly 

 scattered calicocoms are found in small numbers. These are identical with those 

 of H. rohustus. 



Only the lower part of a single specimen of this species is contained m the 

 " Investigator" collection. This was found in the Bay of Bengal 6" 18' N. 90" 

 40' E. in a depth of 2506-2816 m. = 1370-1540 fths. 



EUPLECTELLA, R. Owcn. 



The sponges belonging to this genus are tubular, have a root-tuft, a terminal 

 sieve-plate, and numerous parietal apertures. Parenchymal oxyhexasters are 

 usually present in the interior and floricoms always occur on the surface. Three 

 species, E. simplex, aspera and remlis have been added to this genus by the 

 "Investigator" expedition. 



Euplecti?lla simplex F. E. Sch. 

 \ Plate X. 



1895 EuplecteUa simplex F. E. Sch, in Ab.h. Preuas. Ak. 1895 pp. 15-26, Taf. X. 



In the " Investigator " material there are 10, unfortunately only indiffer- 

 ently preserved specimens of a hitherto undescribed species of Euplectella, which 

 in external appearance and in structure closely resembles Euplectella oweni 

 Marsh, and Herkl. but which essentially differs from this well known Japanese 



