268 ANATOMY AND PHYSIOLOGY 



FIG. 



From the West Indies ? This spiculum is an ex- 

 ternal defensive one. The triradiate rays are im- 

 bedded immediately beneath the dermal membrane, 

 and the spicular ray is projected through it at right 

 angles to its plane ; they are very numerous. 



235. SPICULATED ATTENUATO-EQUIANGULAR TRIRADIATE : 



VERTICILLATELY spiNED. X 660 linear. From an 

 un described sponge. Freemantle, Western Aus- 

 tralia. I have not seen the specimen whence this 

 spiculum is derived, but,, reasoning from our 

 knowledge of the form and situation of the spicu- 

 lum represented by Fig. 234, there can be little 

 doubt of its being an external defensive one. 



236. SPICULATED CYLINDRO-EQUIANGULAR VERTICILLATELY 



SPINED. X 660 linear. Freemantle, Western 

 Australia. From the same slide of Sponge spicula 

 in which the form represented by 235 was found. 

 There can be little doubt of its being an external 

 defensive organ. 



237. INEQUI-FURCATO-TRIRADIATE. X 183 linear. These 



spicula are from a new species of calcareous 

 sponge, probably a Grantia. They were sent to 

 me mounted in Canada balsam by my friend Mr. 

 George Clifton, of Freemantle, Australia. They 

 occur loosely fasciculated, and their mode of dis- 

 position is probably on the surface of the sponge. 

 They differ considerably from each other in length 

 and in the width apart of the prongs of the fork, 

 but they all have them unequal in length. It is 

 probably an auxiliary skeleton and external defen- 

 sive spiculum. 



238 and 239. ATTENUATO-CYLINDRICAL VERTICILLATELY 

 SPINED. X 183 linear. From Hymeraplda ver- 

 ticillata, Bowerbank. These spicula are dispersed 

 in abundance on the interstitial and dermal mem- 

 branes of the sponge. In the young state the 

 spicular are long, slender, and perfectly smooth ; 



