176 A MONOGRAPH OF THE 



IO.Hymeniacidon macilenta, Bowerbanh. 



Sponge. Sessile, coating thinly Zoophytes, &c. Surface 

 smooth, but uneven and rugged. Oscula simple, dis- 

 persed. Pores inconspicuous. Dermal membrane 

 abundantly spiculous ; tension spicula sub-clavate 

 acuate, long and very slender, numerous, dispersed ; 

 and a few tricurvato-acerate, long and slender ; ter- 

 minal curves nearly obsolete ; retentive spicula, inequi- 

 bidentate and dentato-palmate anchorate, the two in 

 about equal quantities, small and few in number; and 

 dentato-palmate anchorate very minute, few in number ; 

 also contort-bihamate, large and very numerous. 

 Skeleton. Spicula sub-clavate acuate, rather short and 

 stout. Interstitial membranes : spicula same as those 

 of the dermal membrane. 



Colour. Alive, scarlet ; dried, dark brown. 

 Habitat. Island of Herm, Rev. A. M. Norman. 

 Examined. In the dried state. 



I received two specimens of this sponge from the Rev. A. 

 M. Norman, each consisting of several fragments ; the largest 

 piece slightly exceeded an inch in length, and was about 

 three lines in width. In the dried state the aspect of the 

 sponge is like that of a thin slice of flesh, roughly dried, 

 with the blood coating it; in the living condition Mr. 

 Norman states that it was of a bright scarlet colour. 



The basal enlargement of the skeleton spicula is usually 

 very slight, and in many of them it is scarcely perceptible, 

 but it is as prevalent in the young skeleton spicula and in 

 the skeleton tension ones as it is in the fully-developed 

 skeleton spicula. The acuate tension spicula are exceedingly 

 slender and long in proportion to their diameter ; they fre- 

 quently attain the length of half that of an adult skeleton 

 one ; the tri-curvate ones also attain about the same length, 

 the central curve is well produced, but the terminal ones are 



