HALICHONDRIA. 105 



dermal membrane is very characteristic of the species. 

 It is thin and pellucid, and is furnished profusely with 

 long, stout, acerate spicula, which are mostly collected 

 into fasciculi containing from two or three to occa- 

 sionally four or five spicula. These fasciculi are 

 irregularly distributed, crossing each other in every 

 direction, and thus producing numerous small irregu- 

 larly shaped arnas, none of which exceed the width of 

 about one-third or one-fourth of the length of a spi- 

 culum. This mode of dermal reticulation is very 

 remarkable, and it is of rare occurrence among the 

 Spongiadse. The skeleton structure is very irregular, 

 and without the slightest approach to definite arrange- 

 ment, and the interstitial cavities usually exceed 

 the length of a spiculum in diameter. The intermar- 

 ginal cavities are also numerous and very large. 



" A fully developed skeleton-spiculum measured g 1 ^ 

 inch in length." 



19. HALICHONDRIA THOMPSON:, Bow., n, 243; in, PI. 



XLIV, figs. 15. 



1867 DenJonjx Thompsoni, Gray. Proc. Zool. Soc., p, 535. 



20. HALICHONDRIA FORCEPS, Bow., n, 244 ; in, PL 



XLIII, figs. 713. 



1874 Halichondria forcipis, Carter. Ann. Nat. Hist., ser. 4, 



vol. xiv, p. 17, pi. xiv, figs. 29 32, and pi. xv, figs. 



37 a, b. 

 1876 Halichondria forcipis, var. bulbosa, Carter. Ann. Nat. 



Hist, ser. 4, vol. xviii, p. 312, pi. xiii, fig. 19, and 



pi. xv, figs. 37 a, b. 



Habitat. Dredged in the " Porcupine " Expedition 



