ERYLUS ROTUNDUS. 291 



fonii C : 1 light-coloured specimen from the coast of Kauai 

 (Station 4128); 

 " D: 1 specimen from the northeast coast of Hawaii 

 (Station 4061); 

 var. cidaris 



1 specimen from the south coast of Molokai (Station 3849). 



Shape and size. The larger (jf the two specimens of var. megarhabda , form A 

 (Plate 5, fig. 32), is upright, somewhat flattened, ellipsoid, 45 mm. high. Its 

 largest and smallest horizontal diameters are 38 and 27 mm. respectively. The 

 surface is i-ugose. The protruding ridges are high and irregular on the apex, 

 lower and arranged in a more regular manner longitudinally, at the sides of the 

 sjxmge. On the apex and the upper parts of the sides numerous circular or 

 oval apertures, 0.1-0.7 mm. in diameter, are observed. The smaller specimen 

 of this form is irregular, massive, 32 mm. long, and in part covered with foreign 

 bodies, attached to the partly undulating, partly nagose surface. There are a 

 few groups of apertures up to 0.8 mm. in diameter. The single specimen of 

 var. mexjarhabda, form B, is irregular, massive, and 23 nam. long. To its rugose 

 surface foreign bodies are attached. There is one group of six conspicuous aper- 

 tures 0.7-1.4 mm. wide on the surface. 



The largest of the four specimens of var. typica, form A (Plate 5, fig. 30), 

 appears as an upright bunch of thick lobose parts, joined for the greater part 

 of their length to form a continuous mass, from the upper side of which their 

 free lobes protrude. The whole sponge is 67 mm. high ; its largest and smallest 

 horizontal diameters measure 69 and 72 mm. respectively. The lobose parts 

 are 16-36 mm. thick and distally rounded. The surface is slightly rugose. On 

 and near the summits of the lobes a few larger apertures, 1-2 mm. wide, are 

 observed ; the sides are occupied by numerous small pores. Considerable parts 

 of the surface are covered by an incrusting composite ascidian (Plate 6, fig. 30). 

 The other three specimens of this form are similar, but smaller, the smallest 

 only 33 mm. high. To the surface of one of them numerous foreign bocUes, 

 fragments of shells, etc., are attached. The largest of the three specimens of 

 var. typica, form B, is an irregular lobose mass, measuring 55 by 51 by 46 mm. 

 It api^ears to be composed of more or less coalesced gyriform parts up to 10 mm. 

 in thickness. Some of these terminate in slightly protruding digitate excres- 

 cences. The surface is penetrated by numerous small apertures and partly 

 covered with symbiotic sponge-crusts and foreign bodies (fragments of shells, 

 etc.). The other two specimens are similar and only slightly smaller. The 



