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the acanthostyle reticulation. Some chelas and smooth tylostyles 

 are mixed in with the spiny spicules of the parenchyma. Toxas 

 occur in both places. 



Principal spicules, acanthostyles to acanthostrongyies (fig. 

 59, C) ; size, 12/* by 120/x, to 12ju, by 140/i. These were interpreted in 

 my earlier paper on this species as acanthotylotes, but further study 

 shows the supposed tylote enlargement of the ends to be merely 

 the somewhat greater spination at these points ; actually this spicule 

 is basically a style, and its pseudotylote shape is derived, I believe, 

 from its attachment at both ends in connection with the very dis- 

 tinctive type of reticulation present. A few that project freely 

 into canals are larger (up to 180/i) and obviously stylote. Ectoso- 



FiGURB 59. — laociona lithophoenix (de Laubenfels) : E, F, X 1,333; others; 



X300 



mal spicules, tylostyles (fig. 59, A) ; size, 3/i by 180/a to 4ju, by 305/i,. 

 Third type of spicules, acanthostyles (not figured) ; size, about 12 fi 

 by 180/t. Fourth type of spicules, smooth styles (fig. 59, B) ; size, 

 9[x by 200ju, to 14/t by ISOju,, rare. First microscleres, palmate isochelas 

 (fig. 59, E, F) ; length, 19/a to 24/a. Second microscleres, toxas (fig. 

 59, Z>) ; length, 23/* to 110/t. 



Remarks. — The only other described species of Isociona is tuberosa 

 Hentschel (1911, p. 326), which lacks the toxas and the rare smooth 

 endosomal styles and has small (4/x by 90/*) endosomal spicules, less 

 spiny than in lithophoenix. This West Australian sponge was 

 dredged from 3 meters. Hentschel described it as Lissodendoryx 

 with much hesitation, commenting that a new genus might be needed. 

 In 1920 (p. 768), Kallmann discussed it further and erected Isociona 

 for it. I agree heartily with Hallmann. 



