28 Mr. H. J. Carter on the Gumminea?. 



very much the appearance of what is seen in Halisarca guttula, 

 and if arrested in this stage of development would be almost 

 identical; but when the cell-mass of the embryo is "told off" 

 into the organs which they are to assume in the fully deve- 

 loped Ascidian, then, of course, the difference at once becomes 

 obvious. 



Still there may be lower forms of the Compound Tunicata 

 which permanently remain in the embryo state of the higher 

 ones ; and this I propose to myself to determine when time and 

 opportunity enable me to hunt for them among the rocks of 

 the sea-shore in this locality. 



All are liable to shortcomings, and Schmidt among the 

 rest, although he is certainly, at present, much beyond all 

 others in actual knowledge of this family ; still I could 

 have wished that he had not compared the nbrilla? of the 

 Gumminese (Die Spong. adriat. Meeres, p. 37, 1862) to the 

 fibrillae of Lieberktihn's Filifera, since the said fibrillae upon 

 which this family of sponges has been built are nothing but a 

 parasite, which I have not only found in different sponges from 

 all quarters of the globe, but especially pervading a species of 

 Reniera like Schmidt's R. Jibulata (Die Spong. des adriat. 

 Meeres, p. 73, pi. vii. f. 9), viz. bearing smooth, fusiform, 

 slightly curved acerates and small bihamates, which is equally 

 cosmopolite. 



In my arrangement of the sponges in the British Museum 

 I have had to expunge the family of "Filifera" in name (Poly- 

 therses, Duchas. et Michelot.) altogether, and for the algal 

 parasite itself on which the family was erroneously founded by 

 Lieberkuhn have proposed the name of " Spongiophaga 

 communis 1 ' 1 (Annals, 1871, vol. viii. p. 330). 



If called upon for a practical definition of the Gummineae, 

 I should say that they are like a piece of yellowish dough in 

 appearance. Incrusting, lobed. Tough, semielastic, subcar- 

 tilaginous. Slippery, smooth. Consisting of a cortical and 

 medullary or body portion : the former translucent and 

 narrow ; the latter opaque, bulky, and massive. The former 

 covered by a thin fibrous cuticle, uniformly pierced by pores 

 and presenting here and there oscula singly or in groups. 

 Composed of a kind of trama formed of fine fibres and minute 

 granuliferous cells, which trama extends throughout the body- 

 mass and affords cavities for the ovoid cells respectively of 

 which the body is composed. The cortex traversed perpendi- 

 cularly by the pore-tubes continued from the pores inwards to 

 unite with the branches of the excretory canals, which, in their 

 turn, traverse the body-mass in tree-like forms to terminate 

 respectively in the oscula mentioned. Abundance of siliceous 



