E. IMPEKIALIS. — SPICULATIOX. 71 



extend right to the upper eml of the body, though not into the 

 sieve-phite. By macerating large specimens and washing away 

 all the free spicules, the wall of the lower half yields a skeletal 

 tube consisting of a continuous, llligree-like latticework of the 

 fused beams (PI. II, fig. 9). The tube is narrowest and firmest 

 at the lower end. At its upper end, the beams are frayed out 

 into their separate fibers. The bundles of anchoring spicules, 

 running along the longitudinal beams in the lowest third of the 

 body, do not participate in the fusion except to a very incon- 

 siderable extent in the deepest parts in direct contact with the 

 beams proper. 



The anchorwcj spicule or the basalia (fig. 16) may reach a 

 length of 200 mm. or more and a breadth of 75 /'. at the middle. 

 The axial-cross lies at some distance (250-320 ,«) from the extreme 

 distal end, which is swollen into the usual miter-shap»ed knob 

 (75-95 ,« long, and nearly as broad) furnished with a whorl of 

 5-9 anchor-teeth. The latter are much smaller and shorter than 

 in E. marshalli or oweni. Soon after its origin from the knob, 

 the shaft is only 19-23// thick. The first barb-like spine, on 

 following the spicule from the distal end, occurs shortly in front 

 of or behind the position of the axial-cross. I observe no 

 definite rule as to the arrangement of the spines on the shaft. 

 They may extend proximally for nearly half the length or more 

 of the entire spicule, imparting to that portion a peculiarly 

 glistening appearance when seen with the naked eye. Proximally 

 they become gradually smaller and wider apart until they altoge- 

 ther cease to exist, leaving the rest of the spicule perfectly 

 smooth up to the finely attenuated upper end. Intermixed among 

 the bundles of basalia-shafts on the sponge-wall, there are always 



