420 Prof. Ehrenberg on Hyalonema lusitanicum, and 



the Portuguese form does there exist a sponge-mass like that of 

 the Japanese. The corium polypigerum in the Portuguese 

 specimens completely covers the whole of the thin end and 

 three-fifths of the axis. The polype-structures occurring at 

 the extremity of the axis are the smallest. The corium and the 

 polypes are formed of several superposed layers of tissue, in 

 which there is a very great quantity of siliceous spicules, which 

 have different forms in the different layers. The shagreened and 

 granular surface of the corium is not a sandy incrustation as in 

 the polypes from Japan, but it is caused by regular clavate sili- 

 ceous spicules, which are spinous all over {Spongolithis clavus, 

 Ehrenb. Monatsb. Berl. Akad. 1861). These clavate spinous 

 spicules form an essential part of the external skin or covering. 

 Each tube, regarded as a polype, is supported by a border of 

 line siliceous spicules, which are deposited in a longitudinal di- 

 rection and at equal distances in the inner wall of the body- 

 cavity. 



From these very meritorious communications of Professor 

 Barboza, it appears most distinctly that the body more than 

 2 feet in length occurring near Setubal in the Portuguese sea 

 certainly answers the question relating to Hyalonema, whether 

 it be a polype or a sponge, in favour of the latter view. 



The long filiform siliceous spicules which, forming a bundle, 

 constitute the axis, are certainly the middle portion of a 

 sponge. This sponge, the structure of which is described in 

 detail by M. Barboza du Bocage as consisting of smaller 

 siliceous spicules, and the numerous orifices of which he regards 

 as the apertures of polypes, covers, as was to be expected, 

 the thin end of the fasciculated siliceous filaments of the axis 

 up to the apex, where, moreover, the above-mentioned efferent 

 apertures (?) are smaller than on the middle and lower part of 

 the body ; so that in a sound state there exists neither a short 

 nor a long tuft of freely projecting siliceous threads. The lower 

 part, which, according to M. Barboza, amounts to two-fifths of 

 the whole length, is therefore free, probably, however, only in 

 consequence of injury in tearing the object away from a firm 

 basal piece, which may perhaps be exactly like that of the upper 

 part. It therefore appears indubitable that the thicker part of 

 all known similar siliceous filaments is the lower part, and the 

 thinner the upper. Consequently the comparison of certain 

 natural orifices in the corium with polypes appears to be not 

 sufficiently well founded. The observer has seen either para- 

 sitic polypes, or merely orifices such as occur so frequently in 

 sponges. Moreover the structure of the so-called corium is 

 completely different from that of the parasitic polype-corium of 

 the Japanese sterns^ which certainly contains demonstrable antho- 



