PLATE LXXX. 265 



HYMBEAPniA SIMPLEX, Boivevdanlc. 

 Plate LXXX. 



Sponge. Coating, very tliin. Surface undulating, 

 sti'ongly liispicl. Oscula simple, dispei'sed. Pores 

 inconspicuous. Dermal membrane pellucid, aspiculous. 

 Skeleton and external defensive spicula attenuato-spi- 

 nulate, very long and slender. Tension spicula long 

 and very slender, frequently sinuous, solitary, or loosely 

 fasciculated. Internal defensive spicula, attenuato- 

 spinulate, entirely incipiently spinous ; spines acutely 

 conical. 



Colour. — In the dried state pale yellow. 



Habitat. — Shetland, ofFBalta; Rev. A. M. Norman. 



Examined. — In tlie dried state. 



I received two specimens of this species from the 

 Rev. A. M. Norman, who dredged them at Shetland, 

 off Balta. They coated very thinly portions of the 

 surface of two small fragments of slate-grey stone. 

 A portion of the largest specimen is represented by the 

 figure. The second one is not more than half the size 

 of the figure one. 



The structures of the sponge are distinctly different 

 from those of any other s^oinulate species of the genus 

 with which I am acquainted. Examined hj direct 

 light with a power of 100 linear it appeared strongly 

 hispid by the projection of the long skeleton spicula 

 through the dermal membrane ; a few of them were in 

 an erect j^osition, but by far the greater number were 

 more or less procumbent. A few simple oscula were 

 to be seen dispersed on the surface, but no indication 

 of pores could be discovered. The greatest thickness 

 of the sponge does not exceed that of stout writing 

 paper, but the length of one of the most perfect of the 

 skeleton spicula was -^^ of an inch, its greatest dia- 

 meter being -9^ inch. This spiculum was in a pro- 

 cumbent position, while others, more or less erect, 

 varied considerably in their height, being from half to 



