BY E. F. HALLMAXK. 537 



latter circunislance may be owing to ilie slightly damaged con- 

 dition of the surface there. The dermal meminane is tJiin and 

 delicate, and easily destroyed. The undamaged surface lias a 

 finely to coarsely granular appearance, due to minute pimple-like 

 elevations of the dermal membrane produced by the impingement 

 upon it of the outer ends of the main skeletal fibres; where the 

 membrane has disappeared, the projecting ends of the fibres 

 render the surface slightly shaggy. The texture is tough, 

 fiVjrous, resilient. The colour in spirit is pule brownish or 

 yellowish-grey. 



The dermal pores are distributed singh', though often in 

 rather close apposition; they are variable in size, "20 to oO/x in 

 diameter. 



Three of the four specimens recorded by Dendy are noted by 

 him as being beset with parasitic Authozoa. The present speci- 

 men is likewise infested, no doubt with the same organism : it 

 is a small, solitary anthozoan, only 1 to 2 mm. in height and 

 diameter, occurring almost completely imbedded in the sponge. 



Skeleton. — The structure of the skeleton, as revealed in sec- 

 tions of the completely desarcodised sponge, in which nothing 

 remains but the spongin-cemented elements (or skeletal frame- 

 work), is ver}' definite and uniform in character, and at first 

 sight, more especially under the lowest powers of the microscope, 

 appears as if more correctly to be described as dendritic than as 

 reticulate (PI. xxxvi., figs.2, 3). It consists almost entirely of 

 ascending, frequently branching, stout main fibres, running 

 moderately closely side by side in subparallelism (at an average 

 distance apart, say, of from 300 to 400/yi), gradually curving out 

 wards, as they ascend, towards the surface. Connecting fibres, 

 however, are by no means rare, but for the most part they are 

 comparatively inconspicuous. The main fibres, which are seldom 

 less than 100/x, and occasionally surpass 200// in stoutness, are 

 formed chiefiy of spicules, for the most part rather loosely and 

 confusedly arranged, a variable proportion (generally a .small 

 minority) of which are dispcsed with their points directed more 

 or less obliquely outwards. As the surface of the sponge is 

 approached, however, the spicules composing the fibres become 



