99 



PLATE XL. 



HALICHONDRIA PANICEA. 



Vol. ii, p. 229, ' Mon. Brit. Spongiadso.' 



Figs. 1,2, 3, 4, are all from St. Catherine's Cave 

 at Tenby. The varieties in their form illustrate in a 

 very striking manner the slight differences in position 

 even in the same locality that appears to determine 

 their modes of development. Figs. 1, 3, and 4, are 

 each uniform in the development of their oscular 

 organs, but fig. 2 is remarkable as combining so many 

 forms of their development, proving that position alone 

 will not determine them to a uniformity of develop- 

 ment. 



Fig. 5. Represents the remarkable variety in form 

 of the species that is described by Ellis in his ' History 

 of Zoophytes,' p. 186, and which was published by him 

 in the ' Philosophical Transactions,' vol. 55, p. 228, 

 Tab. 4, fig. G, under the designation of Cockscomb 

 sponge, and which he states " grows in the rocks to 

 the eastward of Hastings, in Sussex. The common 

 size of it is about three inches long and two inches 

 high." The specimen figured is from the locality 

 named by Ellis. 



The reader must not imagine that the numerous and 

 singular varieties of form that have been figured in 

 the two plates illustrating the species are the whole 

 that might have been represented ; numerous others 

 intermediate between those that have been figured are 

 readily to be found where the species abounds, and in 

 truth it may be said that it has no definite specific 

 form. 



In vol. 1, Plate XIX, fig. 300, a section at right 

 angles to the surface is figured showing the intermar- 

 ginal cavities immediately beneath the dermal surface 

 and the irregular disposition of the skeleton, and in 

 fig. 303 in the same plate a portion of the dermal 

 membrane is represented with the reticulations and 

 pores in the areas in an open condition. 



