324 PBOF. P. M. DUNCAN ON AN 



No flesh-spicules exist on the outside of the cortex, and there 

 is not a trace of any within. A few Globigerince and two or three 

 long and small attenuate spicula were detected ; but they evi- 

 dently are foreign bodies, one spicule exhibiting the results of 



The specimen is characterized by its cylindrical shape and 

 external oscular processes, its smooth and glistening surface, its 

 dense derm of connective foliato-expando-ternate spicula highly 

 dendritic at the edges, its close outer body-spicula with their 

 cylindrical processes of attachment for the connective spicula of 

 the derm, its alternating open and close main structure, with the 

 highly spinulate nature of the quadrifid or tetraclade spicula, 

 and by its deficiency of free stems to the connective spicula, and 

 of all acerates and acuates and other minute sarcodic forms. 



The form is evidently a Lithistid amongst the Siliceo-fibrous 

 Spongida ; and it is indistinctly tetraclade. Amongst the known 

 species of Lithistids with surface-spicula with dendritic edges are 

 MacAndrewia azorica, Gray, which probably is the same thing as 

 Corallistes clavatella, Schmidt, and Kaliapsis cidaris, Bow. 



The new form is neither of these, which, moreover, have 

 flesh- spicula acerate, fusiform, curved, and microspined. I do 

 not wish to establish a new genus from the main characters of 

 this interesting Sponge, and propose to defer the consideration of 

 its classificatory position for a time. Certainly the fixity of the 

 connective derm-spicula is very remarkable. Bowerbank very 

 properly insisted upon the great importance of the free end of the 

 peltate spicula in the growth and swelling out of the sponge ; it 

 enabled the cortex to separate more or less from the body. But 

 in this form every part was rigid ; and in order to grow, the whole 

 of the derm-spicula must have become deciduous. Lately Carter 

 has expressed his belief that the derm-spicula become skeleton 

 forms during growth ; but it does not appear possible in this 

 instance. 



The second specimen of Sponge is cup-shaped, with a narrow, 

 cylindrical, short base expanding below into a ragged foot. It is 

 about half an inch in height, and is composed of one layer of net- 

 work of continuous siliceous spicules. The spaces are large, and 

 the solid part is broken up into minor spaces. Outside are the 

 relics of a derm crowded with derm-spicula. The form clearly 

 belongs to the genus Aphrocallistes, Wright. (Perceval Wright, 



