482 RICHARD EVANS. 



to form the skeletal fibres. These divide and again reunite, 

 produciug an arrangement which is usually described as being 

 reticulate. The fibres are connected together in many places 

 by spicules which bridge over the intermediate spaces. These 

 spicules are the largest in the whole sponge, as a rule, as was 

 found to be the case in Spongilla raoorei. In addition 

 to these there are many spicules, both spiny and smooth, which 

 appear to lie about more or less freely in the tissues. The 

 slender microscleres are nowhere connected with the fibres, but 

 lie absolutely free in the tissues. 



(c) The Spongin. — The spongin is not so highly deve- 

 loped in Spongilla tanganyikse as in Spongilla moorei. 

 The former, therefore, in this respect resembles more closely 

 the ordinary species of the Spongillidse than the latter appears 

 to do. The spongin does not appear to extend to the surface, 

 and the layer which covers the fibres is correspondingly tiiin. 

 The greater development of spongin occurs at the points where 

 the fibres branch or reunite, and at the places where the con- 

 necting spicules penetrate the fibres. 



2. The Gem mule. — Though there was but a small piece of 

 this sponge it happened to contain several gemmules. These 

 are devoid of special spicules, but are surrounded by the 

 ordinary skeletal spicules and the microscleres. They possess 

 a thin coat as in Spongilla moorei, and are spherical and of 

 small size. As regards their cellular contents they present 

 the ordinary characters of the Spongillid gemmule. 



V. The Affinities of Spongilla TANGANYiKiE. 

 This subject must be considered from two aspects. In the 

 first place, the characters of the gemmule must be taken into 

 consideration, since the grouping of the Spongillidae into the 

 three sub-families, Spongillinse, Meyeninse, and Lubomirskinse, 

 and the division of the sub-families into genera, usually adopted, 

 depends on these characters. In the second place, the spicules 

 are of great importance as presenting a close resemblance to the 

 spicules of Lubomirskia intermedia var. a(Dybowski,cf. pi. 

 iv, fig. 3, b, [4]), which belongs to the sub-family Lubomirskinae. 



