41 



PLATE XVI. 



DlCTYOCYLINDKUS VENTILABRUM, 



Yol. ii, p. 100, ' Mon. Brit. Spongiadse.' 



Fig. 1. Represents the sponge half the natural 

 size in its dried state. 



Fig. 2. An acuate skeleton spiculum. X 80 linear. 

 The same figure will suffice to represent one of the 

 external defensive spicula. 



Fig. 3. One of the flexuous acerate skeleton 

 spicula. X 80 linear. 



Fig. 4. A fusiformi, acuate, tension spiculum from 

 the interstitial membranes. X 80 linear. 



Fig. 5. An internal defensive spiculum, entirely 

 but minutely spinous. X 250 linear. 



DICTYOCYLINDEUS RAMOSUS, Bow&rbank. 



Fig. 6. Represents a dried specimen of D. ramosus 

 of about the average size, and in a living condition 

 when it was found, and is a fine specimen of the 

 normal branching form of the species. Natural size. 



Fig. 7. Exhibits the palmate form that frequently 

 occurs to more or less extent in this species. This 

 sponge is one of the most purely palmate specimens 

 that I have yet seen. Natural size. 



Fig. 8. Represents a small palmate specimen, which 

 exhibits the mode by which the palmate form is effected 

 by the branches coalescing laterally. Natural size. 



Fig. 9. One of the acuate spicula of the axial 

 column of the sponge. X 80 linear. This figure also 

 represents one of the radial spicula equally well. 



Fig. 10. Represents one of the cylindrical skeleton 

 spicula from the axial column. X 80 linear. 



Fig. 11. One of the attenuato-acuate, sub-spinu- 

 late internal defensive spicula. X 250 linear. 



Fig. 12. A slender acuate tension spiculum from 

 the interstitial membranes. X 80 linear. 



