REVIEW. 627 



Lieberkuhnii^ without doubt, as it is found at Naples, 

 comes under his definition of the group, and in its fir-tree-like 

 form, branching at right angles into smaller and smaller tubes, 

 shows a stage antecedent to L. tripodifera. Its main oscular 

 tubes are as much (in the specimen before me) as 1*5 cm. by 

 •4 cm. ; its smallest branches about -01 cm. ; between these all 

 intermediate sizes. A most suggestive feature, on which this 

 is not the place to dwell, is that the unpaired rays of the 

 spicules in the branches are mostly distally directed. In 

 Ascaltis cerebrum the oscula (not pseudoscula ; Haeckel 

 was probably misled by the outward appearance when he 

 figured what Dendy would term an " inverted canal-system ") 

 open from spaces 0*3 cm. wide, lined with collared cells con- 

 tinuously up to the granular lip ; its wide tributaries are not 

 superficial as in the oscula of Ascandra reticulum, but 

 deep, and covered with secondary ramifications, ranging down 

 to about '01 cm. diameter. This sponge might seem almost 

 to lead us to Dendy^s Leucosolenia stipitata, placed by 

 him in Section II. But without going further I would point 

 out that the three previous forms all possess triradiates and 

 quadriradiates more or less slender and pointed ; that while 

 those of A. Lieberkuhnii are of nearly the same dimensions as 

 L. tripodifera, and the apical ray similarly curved, A. cere- 

 brum possesses on its external surface the very tripods which 

 give L. tripodifera its name. Will Mr. Dendy consider the 

 possibility that his Radiata may already advantageously step 

 forth as a genus ? e.g. Homocoela. Genus 1. Leucosolenia. 

 The growth of the tubes is mainly confined to new branches ; 

 type L. clathrus, L. dubia. Genus 2. Nardoa. The 

 growth of the tubes is continuous, the newest branches have 

 consequently smallest diameter; type N. tripodifera, N. 

 Lieberkuhnii (?). 



The Reticulata are again divided according as the gastral 

 cavity is or is not traversed by ingrowths of mesoderm. I 

 must state my strong suspicion that the " ingrowths of meso- 



1 For my own observations I use Haeckel's names to avoid the coining of 

 new combinations. 



