228 lilVteEPOOL BIOLOGICAL SOCIETY. 



under the name Eclonemia jjonderosa, B., has, by further 

 examination, turned out to be a Stellettu colling si, B., or at 

 least a variety of it. 



I have found in it all the different kinds of spicules which 

 have been mentioned by Bowerbank, and more recently 

 by Sollas,* and some other spicules in addition to those. 

 The megascleres are — oxea 1'8 by 0*032 mm. ; orthotrigena, 

 the rhabdome of which measures 1"42 by 0*032 mm., and 

 the cladi 0'105 by 0*028 mm. ; a few dichotrisena, the pro- 

 tocladi of which raeasure in length 0"056 to 0*084 mm., and 

 the deuterocladi 0*028 to 0*046 mm. ; and a very few pro- 

 triaena, rhabdome 0*40 mm., cladi 0*036 mm. Both dicho- 

 trisena and protrisena had not been mentioned by previous 

 authors. The microscleres are — chiaster, 0*012 mm. in dia- 

 meter, found only in the ectosome, just beneath the surface ; 

 and oxy asters with a varying number of actines, found 

 chiefly in the choanosome. It seems to be the rule that the 

 larger the oxyasters are, the smaller is the number of their 

 actines. I fomid that — 



4 radiated oxyasters measured 0*056 mm. in diameter 



6 „ „ 0*040 „ 



8 „ „ 0-032 „ 



Besides those above-mentioned kinds of megascleres and 

 microscleres I found an additional kind of spicule which 

 I will call '' prionorrhabds" t (PI. XIV., figs. 1 and 2). 

 They are long and slender spicules, 0*40 by 0*002 mm., 

 one end of which is profusely spined, the other and larger 

 portion is smooth. The two extreme ends of the spicules 

 are sharply pointed. I have found these prionorrhabds 

 only in the ectosome, with their spined ends imbedded 

 in it and the smooth ends projecting through the ecto- 

 derm and penetrating into a calcareous sponge Sijcan- 



* Sollas, loc. cit., p. 185. 

 t From vpiuv a saw. 



