E. OKINOSEANA. — GEN. CHAEACTEKS. 225 



37 mm. by 54 mm. in diameter. In general appearance it agrees 

 well with Eiiplectella marshalli. The beams are mostly y^-l mm. 

 wide, the thinner ones being somewhat laterally compressed but 

 the thicker ones so flattened as to present broader sides exter- 

 nally and internally. In two or three places they join together 

 to form nodal plates 2-4 mm. in width. Among the beams no 

 radial spoke-like arrangement can be discerned. This is in 

 accordance with the absence, in the sieve-plate border, of such 

 large oxypentactins as are present in other species of the genus, 

 w^hich might give rise to a radial arrangement of the beams. 

 The meshes are oval, oblong or angular but always with 

 rounded corners. They measure more usually 1-472 mm. across. 

 An interesting fact is that most of the meshes are each provided, 

 like the paiietal oscula, with a thin, narrow, iris-like membrane 

 that leaves a round aperture in the middle. 



The cuff is very broad with a wavy edge-line, measuring in 

 places 22 mm. in width, and is irregularly undulating, being- 

 directed obliquely upwards and outwards. It is soft and 

 moderately thick. The free edge bears an inconspicuous row of 

 projecting spicules, not more than half a millimeter in length. 



The ledges are low in a narrow zone directly behind the 

 cuff; so also in the basal section of the sponge. In the remain- 

 ing major part of the wall, they are very prominently developed 

 in the form of thick, round-edged and extremely irregular ridges, 

 which vary greatly in height at different points. They may in 

 places be 20 mm. high and 4 mm. or more thick. They frequently 

 branch in their course, making it difficult to determine the 

 general direction they take. Here and there are seen evident 



