28 



centralis is accordingly situated very excentrically and it is attached to the 

 o-astral wall in its whole length. A similar position of the central cone is occa- 

 sionally also met with in the specimens from 8agami Bay (Japan). From the end 

 of the conical, basal part of the sponge a long and slender root-tuft or peduncle 

 protrudes. Unfortunately it is broken off and its lower end is missing. It mea- 

 sures from the point of insertion in the sponge-body to the broken lower end, 

 where the spicules composing it slightly diverge and become isolated, 45 cm. in 

 leno'th. This peduncle is composed of about 30 stout basalia-spicules. Itsupper^ 

 half appears as a firmly, spirally twisted cord 2-5 mm. thick ; in its lower half 

 the spicules are loose and not spirally twisted. The upper end of the peduncle, 

 just below the sponge-body, is enclosed for a length of 2 cm. by the aboral plate 

 of a single Actinia, 8-10 mm. high, 15 mm. broad and 6 mm. thick. Below this 

 it is covered for 20 cm. with the well-known Pahjtlioa {fatiia ?) crust. The 

 lower end is free. 



I shall not enter into a description of the macroscleres, which show no pecu- 

 liarities and resemble those of the specimens from Sagami Bay, but restrict 

 myself to the microscleres, the structure of which is of such great nnportance 

 in the classification of the Hyalonema species. The dermal and the gastral 

 pinules are on an average 150 H- high. The four rays forming their basal cross are 

 straight, stout, rough and % M long. The smooth basal part of the radial main 

 ray is 5 /* thick and pretty short. The distal part is terminally pointed and 

 covered with spines, directed obliquely upwards. In the middle of it the spines 

 are up to 10 fj, long, towards the end and towards the base they decrease in size 

 (pi. VII, f. 4, 5). The canalar pinules in the walls of the excurrent canals are 

 shorter and more slender and have longer basal rays. 



The dermal, gastral and canalar macramphidiscs are on an average 150-200'* 

 long ; their terminal discs are about 40 h- long and broad, nearly hemispherical 

 and have 8 teeth on the slightly-inverted margin (pi. VII, f. 6). The shaft is 

 about 8 f* thick, from its centre four crosswise-arranged tubercles arise. The 

 other parts of the shaft are covered with low, irregularly-scattered protuberances 

 (pi. VII, f. 6). 



Mesamphidiscs are rare. They are about 40-GO i" long, half as broad, and 

 have somewhat elongated, bell-shaped terminal discs with 8 marginal teeth. 



Micramphidiacs are numerous in the gastral and dermal membrane. They 

 are 20-30 /* long, have short hemispherical terminal discs with 10-12 marginal 

 teeth and a slender shaft which is generally thickened in the centre. 



There occur two kinds of parenchymal microhexactines. The one kind with 

 strongly-bent rays 35-40 ^ long and covered with numerous, recurved spines 

 (pi. VII, f. 2), is very abundant; the other kind has somewhat stouter, straight 

 rays, only 25-30 t^ long and covered with strong spines diverging vertically or 

 slightly pointing outwards (pi. VII, f. 3). 



