272 



ERYLUS SOLLASII. 



" 6 fT iT ^ 3 ^ (') 



5 ^ ^ " ^ 3 ? 3 



" ^ 3 7 y C'^ 



The umbilical pit is more or less circular in outline, 30-50 /x broad, and 

 about 15 /I deep. Its walls are usually quite smooth. The rest of the surface 

 of the adult aspidaster is covered with protruding rays, often somewhat irregu- 

 larly distributed, and 1.4-1.7 /.( thick. These rays bear terminal verticils of 

 usually six to eight lateral spines (Plate 4, figs. 36, 37). The youngest aspid- 

 asters observed were about 55 p. long and appeared as oval, radially striated 

 discs with deeply serrated margins. In a more advanced stage these spicules 

 are smooth discs with slightly undulating margins. On the faces and the 

 margin of such, small protuberances then make their appearance and these 

 grow out to form the protruding rays of the adult aspidastcrs above described. 

 The centre of the aspidaster is occupied by a rosette-shaped granule about 1.7 

 in diameter. Viewed in profile the adult aspidasters show a distinct stratifica- 

 tion. The limits of the layers are smooth and nearly parallel to the two faces. 

 Viewed en face they show fine straight striae radiating from the central granule. 



This sponge was trawled in the Galapagos Islands, Station 2809, on April 

 4, 1888; 0° 50' S., 89° 36' W.; depth 82 m. (45 f.); it grew on a bottom of gray 

 sand; the bottom temperature was 23.4° (74.1° F.). 



The only known species which appears to be allied to the s])onge described 

 above is E. polyaster Lendenfeld from the Agulhas bank, South Africa. From 

 this it differs, apart from minor peculiarities, by the aspidasters, which are, 

 absolutely and relatively more than three times as thick in E. polyaster 

 as in E. oxyaster, a difference, of course, quite sufficient for specific distinction. 



Erylus sollasii, sp. nov. 

 Plate 1, figs. 1-48; Plate 2, fig.s. 1-26; Plate 3, figs. 1-28. 



I establish this species for seven specimens obtained at five stations among 

 the Hawaiian Islands. Among the known species of Erylus the one named after 

 me by Sollas appears to be its nearest ally. I therefore return my distin- 

 guished friend's compliment by naming this new species after him. 



The two specimens from Station 3847 are both small ; one is partly light, 

 partly dark in colour; in the other the whole of the surface is dark. Both the 

 specimens from Station 3848 are large and whitish. The specimens from Sta- 

 tions 3849 and 4055 are large and dark. The specimen from Station 4062 is 

 middle sized and fight coloured. 



The two specimens from Station 3848 are in every way identical ; all the 

 others differ to some extent from these and from each other. We have to deal 

 therefore with six different forms. As is shown below, these six forms fall into 



