Species of Echinunematous Sponge. 
27 
Plate VI. 
Plectronella papillosa. 
Fig. 22. Triradiate variety ; spined ray and one smooth one lying in the 
same straight line, with which the second smooth ray makes 
almost a right angle. 
Fig. 23. Triradiate variety; one smooth ray terminated bluntly, the 
other one pointed. 
Fig. 24. Triradiate variety ; one smooth ray making an angle nearly 90° 
less than usual with the spined ray. 
Fig. 25. Triradiate variety; both smooth rays stunted and with rounded 
ends ; a large erect spine projects from one side. 
Fig. 26. Triradiate, equiangulate, very slightly spined. (This is the 
form figured by Bowerbank, Monograph Brit. Spong. vol. i. pi. v. 
fig. 88, and described by him as equiangulate, triradiate, uni- 
radiately spined ; he obtained it from a small fragment of a 
parasitic sponge.) 
Fig. 27. Similar form, showing the canaliculation of the spines. 
Fig. 28. Quadriradiate variety. 
Fig. 29. Similar but much younger variety. 
Fig. 30. Young form of triradiate spicule. 
Fig. 31. Triradiate variety, with both smooth rays inclined approxi¬ 
mately at right angles to the spined one. 
Fig. 32. Quadriradiate, with a very long spined ray, and showing the 
canals of the spines. (Figures on PI. VI. all X 315.) 
Plate VII. 
Dercitus Bucklandi. 
Fig. 33. Equiangular triradiate variety. 
Fig. 34. Quadriradiate, with one arm longer than the others and one sub¬ 
divided into two rays of unequal length. 
Fig. 35. Quinqueradiate variety, with one ray fiexed, and another bifur¬ 
cated and once spined. 
Fig. 36. Biradiate variety, with one ray bifurcated. 
Fig. 37. Quadriradiate, one ray giving off a branch or a spine in a back¬ 
ward direction. 
Fig. 38. Quinqueradiate rectangular variety. 
Fig. 39. Quadriradiate with two rays flexed at the end and one ray 
bifurcated ; ends of bifurcated ray, one rounded off hemispheri- 
cally, the other incompletely bifurcated a second time. 
Fig. 40. Quadriradiate with one ray bifurcated. 
Fig. 41. Quinqueradiate similar to fig. 38. 
Fig. 42. Quadriradiate with two arms flexed in opposite directions and 
two straight. 
Fig. 43. Quadriradiate, one ray flexed. 
Fig. 44. Quadriradiate with one ray terminated hemispherically. 
Fig. 45. Quadriradiate; one ray flexed first to one side and then to the 
other so as to regain its original direction, one ray flexed and 
rounded hemispherically, a third simply rounded off at the end, 
and the fourth unaffected. 
Fig. 46. Two quadriradiates ankvlosed by the rays a and b. 
The Museum, Bristol, 
Sept. 20, 1878. 
