38 Dr. J. V. Barboza du Bocage on Hyalonema boreale. 
communicate to you, because they completely change my first 
impression. 
The axis or stem of the sponge is composed of an aggre- 
gation of linear spicules. I thought at first that each of these 
spicules extended uninterruptedly, like those of Hyalonema, 
from the base to the apex; but I have now ascertained that 
these spicules are, on the contrary, short in proportion to the 
dimensions of the axis, and that it is by their regular aggre- 
gation that this axis is formed. To make myself more intel- 
ligible, I will say that the axis does not at all resemble that 
of Hyalonema, but is constituted as in figure 2. 
The axis of Hyalonema boreale seems to me to present an 
identical structure; but Lovén has not noticed all the impor- 
tance of this difference as compared with the true Hyalonemata. 
In my opinion, therefore, my two little sponges are not, as 
I at first thought, the young of Hyalonema lusitanicum ; on 
the contrary, | am convinced that they must belong to a 
perfectly distinct genus, which I intend to name Lovenia. 
To this same genus Hyalonema boreale, Lovén, must belong ; 
it is perhaps identical with my two specimens. The only differ- 
ence of any importance which prevents my proposing this iden- 
tification is that Lovén does not seem to have detected the spiny 
spicules implanted in the sarcode in his two specimens, whilst 
the surface of mine is covered with them. Perhaps this appa- 
rent difference is only the result of an imperfect observation. 
The new genus Lovenia will therefore be characterized by 
the existence of a solid axis or stem composed of an aggre- 
gation of short linear spicules, covered by a very distinct layer 
of sarcode, in which are implanted small defensive spicules 
analogous to those of the genus Aphrocallistes, according to 
the drawing published by Wyville Thomson (Ann. & Mag. 
Nat. Hist., February 1868). This stem is surmounted by a 
rounded head composed of radiating filaments, formed by 
linear spicules analogous to those of the stem. Other linear 
spicules, but shorter and in the form of little bacilli, are im- 
planted perpendicularly to the surface of the head and in the 
spreading part of the base. . 
I am busy at present studying the structure of the sponges 
which accompany many of my specimens of Hyalonema lusi- 
tanicum, and I shall soon communicate to you the results of 
my observations. 
The pertinacity with which Dr. Bowerbank regards the 
animals of the Palythoa as the oscula of a sponge, astonishes 
me more and more whenever I think of it! 
You will soon hear from me again. Believe me, your 
devoted friend, J. V. BARBOZA DU BOCAGE. 
