281 



PLATE LXXXIV. 



DiCTYOCYLiNDitus EECTANGULUS, JJowerbaiik. 



Eig. 1 — Represents the type-specimen in tlie cabinet 

 of tlie Rev. A. M. Norman of the natural size. The 

 detached piece near the top of the plate with the X at 

 its base is a continuation of the main stem of the 

 sponge from the spot at the top indicated by a corre- 

 ponding mark. 



Fig. 2. — One of the large acuate external defensive 

 sjDicula. X 80 linear. 



Fig. 3. — One of the long and very slender acuate 

 tension spicula of the dermal membrane. x 80 

 linear. 



Fig. 4.— An average-sized acuate spicuhmi from the 

 axial skeleton of the sponge ; occasionally they attain 

 the size of the external defensive ones represented by 

 figure 2. X 80 linear. 



Fig. 5. — A cylindrical skeleton spiculum. X 80 

 linear. 



Fig. 6. — An acerate skeleton spiculum. X 80 linear. 

 The spicula represented by figures 5 and 6 are of com- 

 paratively rare occurrence. 



Fig. 7. — One of the entirely sjoined, attenuato -acuate, 

 internal defensive spicula. X 2-50 linear. 



DicTYOCYLiNDEUS EECTANGULUS, Boiverbcmk. 



Plate LXXXIV. 



Sponge ramous, slender ; branches regularly cylin- 

 drical; primary branches dividing dichotomously or 

 trichotomously ; secondary branches at right angles to 

 the primary ones ; surface hispid, External defensive 



