34 PLATE XIII. 



cloacal appendages of the sponge, exhibiting the cen- 

 tral column with the small cylindrical pedicles or short 

 fasciculi of closely packed spicula, each terminating at 

 the inner surface of the dermis of the sponge of the 

 natural size, taken from the largest of the two speci- 

 mens described. 



Pig. 361 in the same plate is from a section of the 

 sjDecimen represented by fig. 360 at about the middle 

 of the cloacal column, exhibiting the mode of the 

 radiation of the distal ends of the small pedicles on the 

 inner surface of the dermis. X 25 linear. 



I have two other specimens of this sponge beside 

 those previously described. One of them has the base 

 two inches in length by ten lines in width. It is three 

 and a half inches in height, and has four large penicillate 

 organs, which have their origin within half an inch of 

 the base of the sponge. The other specimen has a flat 

 base, two inches in length by one and a half inch in 

 width. It has fifteen small penicillate organs on its 

 upper surface, none of which exceed eight lines in 

 height and about one line and a half in diameter. The 

 greatest height of the sponge does not exceed ten hues. 

 In every anatomical character the last two sponges are 

 in perfect accordance with the former two. 



The species C. penityillus is the only British one 

 known, but there is another species from Port Eliza- 

 beth, Australia, two specimens of which are in the 

 cabinet of my friend Captain Charles Tyler. They so 

 closely resemble the British species in their external 

 characters and in the mode of the arrangement of their 

 skeleton structures as to render it quite impossible to 

 distinguish the one from the other excepting by the aid 

 of the microscope. The skeleton of the British species 

 is then seen to be composed of stout, fusiform, acuate 

 spicula, while that of the Australian species is formed 

 of acerate spicula ; excepting this important character, 

 they certainly could not be separated from each other. 



