Marine Sponges from Japan. 405 



forms of rays in the same figure, viz. a, the pointed, and b, the 

 capitate rays. For the sake of perspicuity only two or three of 

 the rays are delineated. 



Fig. 10. The same. More magnified view of the sexradiate of the basal 

 structure. 



Fig. 11. The same. Portion of the dermal structure, magnified upon the 

 scale of l-48th to 1-1 800th inch, showing the sexradiate dermal 

 spicules, the heads of the clavulee around the aborted external 

 ray aud the pores, ah 1 in situ, a, single clavulee, occasionally 

 seen along the line of reticulation. 



Plate XIV. 



Fig. 1. Hexactinella ventUabrum, n. sp. Fragment of the inner surface, 



to show the vents. Natural size. 

 Fig. 2. The same. Fragment of outer surface, showing the dermal reti- 

 culation and subjacent apertures in the body -substance leading 

 to the vents, a, portion covered by the dermal structure ; b, 

 portion from which it has been removed. Nat. size. 

 Tig. 3. The same. Vertical section of the wall, to show its plumose 



structure. Nat. size. All diagrams after nature. 

 Fig. 4. The same. Group illustrative of all the spicular elements, drawn 

 to the scale of l-24th to 1-lSOOth inch, to show their relative 

 sizes, a, main fibre ; b, sexradiate of the interior; c, scopula ; 

 (I, rosette ; e, hexactinellid acerate of the interior (stout form) ; 

 /, the same of the dermis (finer form); g, sexradiate of the 

 exterior or dermis. Diagrammatic after nature. 

 Fig. 5. The same. Scopula with three rays, much magnified. 

 Fig. 6. The same. Rosette, much magnified, showing— a, form with lono- 

 simple pointed rays, sometimes capitate; b, with short rays", 

 always capitate. Only two or three rays to each arm delineated,' 

 for the sake of perspicuity. 

 Fig. 7. The same. Another form of the rosette often met with. (Figs. 5 



6, and 7 drawn to the same scale.) 

 Fig. 8. The same. Vertical section of wall, magnified about four dia- 

 meters, to show character and direction of the plumose fibre. 

 Fig. 9. The same. Fragment of dermal structure, to show reticular 



arrangement of the sexradiates and situation of the pores. 

 Fig. 10. The same. Sexradiate of the interior, more magnified, to show 



that its arms are spiniferous. 

 Fig. 11. Racodiseula asteroides. Spiculation of surface, magnified to the 

 scale of l-24th to l-1800th inch, a, upper view of disk, showing 

 the three arms of the central canal, which indicate the forth- 

 coming upper three branches of the tetractinellid or staple spi- 

 cule of the structure ; b, lateral view of the disk, showing the 

 spine on its under surface, indicating the position of the fourth 

 branch ; c, small microspined acerate ; d, minute elliptical body 

 or spicule ; e, large smooth acerate ; /, more magnified view of 

 " c " ; g, more magnified upper and lateral views of " </" respec- 

 tively. r 

 Fig. 12. Chalina poly chit oma, var. mauritiana. Spicule of Japanese 



specimen. 

 Fig. 13. The same from the Mauritius specimen, together with 

 a more curved form. (Figs. 12 and 13 magnified to the same 

 scale, viz. l-48th to l-6000th inch, to show their sizes rela- 

 tively.) 



Ann. & May. N. Hist. Ser. 5. Vol. xv. 28 



