426 Prof. Ehrenberg on Hyalonema lusitanicum. 



The whole of these Spongolithes are, indeed, most like isolated, 

 variously entangled tubular cells; but in Hyalonema they acquire 

 the perfect character of long connected liber-tubes. 



Quite different is the behaviour of the calcareous parts of the 

 Radiata and Aiithozoarian Polypes, which, although often fusi- 

 form, have no canal, and are frequently net-like and variable in 

 form. All these, named Zoolitharia by me in 1841, remind us 

 of the first isolated developments of the bones, shells, and hard 

 cutaneous parts of animals, the aggregations of which are solid 

 and (because like calcareous sinter) doubly refractive. Even 

 the anchor-like organs of the skin of many Echinodermata 

 [Synapta) are seated upon reticulated calcareous plates, and are 

 articulated in the manner of the s])incs of the sea-urchins 

 {Cidaris) ; they have consequently, except in form, no relation 

 to the anchors of the Spongillce. They arc calcareous setae with 

 barbs. 



Summary, 



1. Thus the Portuguese Hyalonema is not a Polype, but a 

 S])onge. 



2. The Sponges themselves arc without those decisive cha- 

 racters of independent animal bodies which have been detected 

 down to the smallest monads. 



3. The essential characters of the Sponges coincide without 

 difficulty with those of vegetable structure, inasmuch as their 

 supposed animal characters, automatic ciliary movement, swarm- 

 ing young and spermatozoids, and some contractility, as also a 

 movement of the juices, have been recognized in both kingdoms. 



4. The siliceous parts of the Sponges, or Spongolithes, appear 

 to have a great analogy to usually innumerably isolated, smooth, 

 juice-bearing vascular cells, like the thick-wallcd liber-cells of 

 j)lants, with which they coincide also in the most various forms, 

 but to have no similarity to any structures in the animal bod}^ — 

 in the Hyalonema~thi-eSids even resembling internal liber-tubes 

 of two feet long. 



5. The supposed normally protruding tufts of Hyalonema ap- 

 pear, when they occur on true sponge-structures, to be mutila- 

 tions by the loss of the apices of these sponges, like the dead 

 points of the horny corals, just as the deciduous trees in the 

 north or on elevations often bear antler-like dead summits 

 whilst the trunk is still well furnished with foliage. 



6. The Euplectellce, described by Owen in the years 1811 

 and 1857 as E. aspergillum and E. cucumer, the latter from the 

 Seychelles, and the former from the Philippine Islands, exhi- 

 bited to their very meritorious discoverer, who only saw them 

 in a dry state, a gelatinous interstitial mass, but no trace of 



