10 PEOCEEDINGS OF THE NATIONAL, MUSEUM vol.81 



osculum, measuring 3 mm in diameter. Specimen D is a com- 

 pomid body potatolike in form and provided with three circular 

 oscular apertures measuring 2 mm on the top, two of which open 

 close together, while the third one is situated somewhat apart from 

 the others. 



All the specimens labeled B to D have numerous weak, short, 

 prostal lateralia protruding from the entire surface of the body, 

 and the basal tuft is not prominently formed. The basal anchor 

 spicules project separately from the basal surface. 



Spiculation. — The numerous radial cuspidates (fig. 1, Z), project- 

 ing a very short distance beyond the surface of the sponge, are long 

 spicules, thickly covered with pointed microspines on the proximal 

 surface imbedded in the sponge wall and becoming gradually sparser 

 and larger toward the apex. They occur on all surfaces, espe- 

 cially at the basal regions of the body and are always radially dis- 

 posed, so that the pointed ends of the bars are directed inward and 

 the anterior point of the whole spicule outward. The distal end, 

 somewhat expanded to a globular form, is provided laterally with 

 two short spines projecting slightly outward. I have found only one 

 specimen (D) in which these protruding spicules are much stouter, 

 longer, and arranged in a bundle; they usually project singly. 



The root spicules (fig. 1, m) do not form a tuft; they protrude 

 singly from the basal surface of the sponge body, infrequently 

 making a small curled bundle. These long, strongly developed 

 spicules end internally in the body in a simple point ; while, toward 

 the lower and outer end, they first decrease gradually in thickness 

 and then finall}'^ form a double-toothed, gently curved anchor. Two 

 anchorlike teeth stand out almost at right angles from the shaft; 

 are only slightly bent, and end in a somewhat blunt point. In 

 specimens B to D, 25-37 mm in diameter, the basalia project singly; 

 and, as the sponge grows, the spicules composing the basal tuft 

 increase in number and in size. 



The hypodermalia (fig. 1, 6) are composed of the large pentactins 

 supporting the dermal membrane; the four paratangentials lie 

 mostl}^ in a plane and extend tangentially to the radially arranged 

 rays of starlike texture on the dermal surface, measuring 320/x to 

 1,700/A in length. The spicules vary greatly in size ; the larger ones 

 measure lOoju, to l,200ju, along the proximal ray and 320/a to l,TOO/x 

 across the paratangential rays. The rays are quite smooth, and 

 usually taper toward the sharp-pointed end, with a breadth of 16/^ to 

 160^ at the base. 



In certain parts of the dermal and gastral membranes, uncinates 

 1 mm to 3 mm or more in length and up to IG/x thick occur, some- 



