AULOSACCUS MITSUKURII. 121 



selves and in tlie deep part of the cavity there are some that 

 reach G mm. in diameter. 



The second specimen (O. C. No. 4399) I have seen of the 

 species was from an unknown locality in the Sagami Sea. It 

 was collapsed and incomplete, lacking the basal part. Length, 

 225 mm. Greatest breadth, 130 mm. Average thickness of wall, 

 16 mm. The piece must have originally formed a great part of 

 a large individual. The one end still preserved a section of the 

 oscular margin ; the state of the parenchymalia at the other end 

 indicated proximity to the basal attachment. The external sur- 

 face was badly lacerated but still showed traces of the conuli. 

 The prostalia had all been lost. Some of the canalar apertures 

 on that side were as much as 5 mm. in width. The endosomal 

 skeleton remained in good preservation, covering over the excur- 

 rent canalar apertures. 



Spiculation. 



PL X., fig. 11, represents in a general way the spiculation 

 as observed on a section of the sponge-wall. 



The parenchymalia are all diactins which are generally 

 smooth throughout except subterminally for a short space where 

 the surface is roughened in the well-known manner. Of rather 

 common occurrence are the strong principalia which may attain 

 a length of 20 mm. and a thickness oF nearly f mm. at the 

 middle. These have gradually tapering and acuminate rays and 

 are therefore to be called oxydiactins. They are bent in a bow- 

 like manner but are otherwise nearly straight. The rest and by 

 far the greater number of the parenchymalia are more slender 

 spicules, there existing all sizes transitional between the strongest 



