1887.] NATURAL SCIENCES OF PHILADELPHIA. 175 



more gradually pointed. Their thread-like fascicles form a compact 

 network. The gemmul?e spicules are smooth, symmetrically bent 

 near each end, and form a thick layer around the gemmules ; but 

 are sparingly distributed tli rough the tissues. The gemmulaj have 

 a tolerably thick outer wall and are found everywhere in the 

 sponge." 



"Habitat: Altrheim (?) near Eggenstein, (in the vicinity of 

 " Karlsruhe). According to Prof. Niisslin, whom I thank for the 

 specimens, the sponge when living is green, and at all times can 

 be found on fiiscine bushes (Faschine7i gestraeuch.") 



Through the kindness of Prof Eimer in Tubingen, I was enabled 

 to examine a fragment of EuspongiUa rhenana, and can offer some 

 additions to the description of lietzer. 



The gemmulffi have the form and size of those of E. lacustris, but 

 the polar aperture (mikrodiode) is surrounded by a broad, plate-like 

 funnel. Upon the chitinous membrane is a very thin air-chamber- 

 layer consisting of 2-3 cells overlying one another. This layer was 

 rarely deeper than 5-0 cells in a column. The latter support the 

 greater number of spicules. They generally lie tangentially upon 

 the surface of tlie genunule and very few are embedded radially in 

 the air-chamber-layer. In shape these spicules are very variable, 

 and generally three principal forms can be determined. The most 

 plentiful are those which resemble the common skeleton spicules ; a 

 very few, those mentioned by Retzer, are bent double and such are 

 also scattered singly through tlie parenchyma; finally, there are 

 found upon the surface of the gemmulae, spicules that are slightly 

 ))ent and compressed in the centre. 



The auxiliary apertures (neben-mikrodioden), numbering 3-6, upon 

 the surface of the gemmulse, are worthy of notice. About every 

 tenth gemmule has, near the principal aperture, some lateral fun- 

 nels ; which fact makes this form resemble the species described by 

 ( 'arter from British Columbia, under the name of Spongilla multi- 

 poris. 



(b) Sub-gen. SPONGILLA, Wierzejski. 

 From 2-30 gemmulse as a rule, grouped in a common covering, 

 or placed pavement-like along side of one another. Mostly there is 

 a deep air-chamber-layer, through which smooth and rougli spicules 

 are scattered. 



