or THE SPONGIAD^. 209 



Britisli Sponges/ but as I have already proposed to restrict 

 the term Halichondria to those species which agree in 

 structure with the original type of that genus, H. panicea, 

 Johnston, it becomes necessary to select other names to 

 represent the sponges which differ essentially in their struc- 

 ture from that type, and I therefore propose to adopt 

 Dr. Grant's genus Chalina, designated in his ' Tabular View 

 of the Animal Kingdom,' published in 1861, to represent 

 that portion of them which agree in structure with the well- 

 known species described in the * History of the British 

 Sponges' as Halichondria ocuiata. Fig. 263, Plate XIII, 

 represents the fibres of Chalina ocuiata, Bowerbank {Hali- 

 •chondria, Johnston), illustrating the structure of spieulated 

 keratose fibre, and Kg. 263 exhibits the mode of growth 

 of the fibre in Chalina Montagui, Bowerbank, («) the 

 apical spiculum of the growing fibre. 



Suborder IV. Simple -fistulo-kerato-fibrous skeletons. 



The type of this suborder is Lamarck's Spongia fistnlom. 

 The anatomical structure and the general habits of the 

 sponges of this description are so widely different from the 

 true Spongias, that I was induced to estabhsh them as a sepa- 

 rate genus, and I accordingly designated and described them 

 as such in the ' Annals and Magazine of Natural History' 

 for December, 1845, vol. xvi, p. 400, plate xiii, fig. 7. It is 

 unnecessary to enter here into a detailed account of these 

 tissues, as I have described the peculiarities of the struc- 

 ture of the simple fistulo-keratose fibrous skeletons at length 

 in describing the ixature and structure of the fibrous tissues 

 of Spongiadae. Fig. 266, Plate XIII, represents the simple 

 keratose fibre from BpongiufiduUns, Lamar*, X lO'S linear. 



The 'genus m^ay be diaracterised as follows -. 



Veeongia, Bowefbawk. 



Skeleton kerato-fibrous- Fibres cylindrical, icontiffluous'ly 

 fistulose^ aspiculous. Rete ansymmetrioal. 



14 



