1 68 PORIFERA 



Then Biitschli ^ (1884) and Sollas^ on combined morphological 

 and embryological evidence (1884) concluded that sponges were 

 remote from all the Metazoa, showing bonds only with Choano- 

 flagellate Protozoa (p. 121). This the exact embryological work of 

 ^laas, Minchin, and Delage has done much to prove, but it has to 

 be admitted that unanimity on the exact position of the phylum has 

 not yet been attained, some authorities, such as Haeckel, Schulze, 

 and Maas still wishing to include sponges in the Metazoa. 



In this short history we have been obliged to refer only to 

 work helping directly to solve the problem of the nature of a 

 sponge, hence many names are absent which we should have 

 wished to mention. 



Halichondria panicea. 



One of the commonest of British sponges, which may be 

 picked up on almost any of our beaches, and which has also a 

 cosmopolitan distribution, is known by the clumsy popular name 

 of the " crumb of bread sponge," alluding to its consistency ; or 

 by the above technical name, with which even more serious fault 

 may be found.' 



In its outward form H. panicea affords an excellent case of a 

 peculiarity common among sponges. Its appearance varies ac- 

 cording to the position in which it has lived. In fact, Bowerbank 

 remarks that it has no specific form. It may grow in sheets 

 of varying thickness closely attached to a rock, when it is 

 " encrusting," or it is frequently massive and lying free on the sea 

 bottom ; again, it may be fistular, consisting of a single long tube, or 

 it may be ridge-like, apparently in this case consisting of a row of 

 long tubes fused laterally. In this last form it used to be called 

 the " cockscomb sponge," having been taken for a distinct species. 



Bidder has proposed to call the different forms of the same 

 species " metamps " of the species. Figures of the metamps of 

 H. panicea will be found in Bowerbank's useful Monograph.* 



1 Ann. Mag. Nat. Hist. (5) xiii. 1884, p. 381. 



' Quart. Journ. Micr. Sci. xxiv. 1884, p. 612. 



^ The name was coined by Dr. Fleming from x^^'^ "silex" and x^'^P"^ "car- 

 tilage," and as these roots could only give Clialic-chondria it is not surprising that 

 those who have not referred to Dr. Fleming's statements give the derivation as 

 fiXs " sea " and xiS^Spos. 



■* Monograph of British Sponges, vol. iii. pi. xxxix.-xl. For revision of nomen- 

 clature in this Monograph, see Hanitsch, Tr. Liverp. Biol. Soc. viii. 1894, p. 173. 



