41 



PLATE XVI. 



DiCTTOCYLINDEUS VENTILABliUM, BoWPrhoMlL 

 Vol. ii, p. 100, ' Mon. Brit. SpoiigiadiE.' 



Fig. 1. — Represents the sponge half tlie natural 

 size in its dried state. 



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

 The same figure will suffice to I'eprescnt one of the 

 external defensive spicula. 



Fig. 3. — One of the flexuous acerate skeleton 

 spicula. X 80 linear. 



Fig. 4.- — A fnsiformi, acuate, tension spiculum from 

 the interstitial membranes. X 80 linear. 



Fig. 5. — An internal defensive spiculum, entirely 

 but minutely spinous. X 250 linear. 



DiCTYOOYLiNDRUS EAMOSUS, Bowerhan]:. 



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. Natiu'al size. 



Fig. 8. — Represents a small palmate specimen, which 

 exhibits the mode by which the j^almate form is efi^ected 

 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. 



