85 



of little use to describe these spicules, some or all of which may have been 

 introduced into the specimen from outside, in a more detailed manner. Only 

 one of these various kinds of spicules, which occurs pretty frequently in the 

 midst of the densest part of the fibre-mass, and which may therefore probably 

 be considered as proper to the sponge, is worthy of closer study. These spicules 

 are peculiar, concentrically stratified spheres. I have represented them, magni- 

 fied 100 diameters, in figs. 12-14 on plate IX. They closely resemble the 

 " silica-pearls " which I first found in Pheronema giganteum F. B. Sch. in 1893 

 and which I have described in the Sitzungsberichte der Berliner Akademie for 

 1893, p. 996. Some of them are quite smooth, the surface of others is tubercu- 

 lous or spined. In some of the larger ones we find on the surface irregularly 

 distributed, smooth convexities, divided from each other by striated grooves 

 which extend in various directions. 



This fragment was found in the western part of the Bay of Bengal, 12° 10' 

 N. 85° 8' E. in a depth of 3300 m.=1803 fths. 



The second of these fragments consists of an entirely macerated skeleton- 

 net and has the size of a walnut. The strands of the network are joined in a 

 quite irregular manner and enclose several cavities, communicating with each 

 other and appearing as passages, 5 mm. wide and circular in transverse section. 

 The irregular network forming the walls of these passages is perforated by 

 several nearly round apertures, 2-3 mm. in diameter, so that the whole, to a cer- 

 tain extent, becomes similar to the skeleton of Bhabdodidyum delicatum O. 

 Schmidt. It is probable that this sponge belongs to the species mentioned, of 

 which only the supporting skeleton-net is known. 



This skeleton-fragment was found in the middle of the southern part of the 

 Bay of Bengal 6° 18' N. 90° 40' E. in a depth of 2506-2816 m.=1370-1540 fths. 



IV. FARREIDAE. 



Uncinataria composed of systems of tubes tending to anastomose. The 

 dictyonal skeleton is m the younger portion of the sponge a simple network 

 with quadratic meshes. With clavules. * 



Faerba Bowerbank. 



Systems of tubes, branching dichotomously and tending to anastomose, 

 which are distally sometimes extended in a caliculate manner. On the dermal, 

 as well on the gastral surface clavules occur together with the uncinates. Sco- 

 pules are always absent. 



