236 ANATOMT AND PHTSIOLOGT 



Tig. 



53. Spiculated kichotomo-patento-ternate. — A still 



more complicated form than that of the Purcated 

 patento-temate one. The radii of the bifurcations 

 each terminating again dichotomously j but the 

 secondary bifurcations are not all of them in the 

 same plane as the primary ones, a portion of them 

 being at right angles to it, and the shaft is also 

 carried through the common central base of the 

 whole, giving it a spic dated form as represented 

 in the figure. X 260 linear. Sponge unknown. 

 Similar spicula occur abundantly in the dermis of 

 Dactylocalyx Bowerhankii, Johnson, in the British 

 Museum. X 260 linear, Page 18. 



54. Recurvo-teenate. — ^The terminating radii, recurved 



from about 100 to 140 degrees from the apical 

 line of the axis of the shaft. The curves of the 

 radii are always more or less inclined towards the 

 base of the shaft of the spiculum. Prom Geodia 

 Barretti, Bowerbank, MS. X 90 linear. Page 

 123. 



55. Spiculated recurvo-ternate. — Having three equi- 



distant recurved radii, and the central terminal one 

 porrect in the line of the axis of the shaft of the 

 spiculum. From Geodia Barretti, Bowerbank, 

 MS. X 90 linear. Page 22. 



56. The central porrect terminal ray is often more or less 



deflected from the axial line of the shaft, as in 

 Pig. 56 ; and occasionally, in the simple recurvo- 

 ternate form, one of the three rays will be bent 

 upward, even to a greater extent than is repre- 

 sented in Fig. 57 ; but these it must be recollected, 

 are but accidental variations in form. 



57. The shafts of the recurvo-ternate forms of spicula are 



much less in diameter than those of the patento or 

 expando-ternate ones from the same sponge, and 

 they are frequently very long and exceedingly 

 attenuated. 



