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 horeale seems to me to present an 

 identical structure ; but Lovdn 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, I am convinced that they must belong to a 

 perfectly distinct genus, which I intend to name Lovenia. 



To this same genus Hyalonema horeale, Loven, 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 Lovdn 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 AphrocalUstes, 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. y. Barboza du Bocage. 



