sponges from the Atlantic Ocean. 815 



ends respectively, much expanded, 8- hy /ii-GOOOths inch 

 (PI, XIll. fi^. 17,/") ; 2, bilian)jitcor lil)ula, simple, (J- or S- 

 shapcd, subspiral, 2()-GO0Otli.s inch long {\v^. 17,//). The 

 8kelcton-s{)ifule8 make up the chirl" part uf the dermal and 

 internal .strnctures, both ot" whieh are plentifully charged with 

 each kind ot" tlesh-spieule. Size of specimen It*^- inch long, 

 tV inch broad, and -^'^ inch high; tubular ])rolongations ^ inch 

 long by Vt inch broad at the free extremity, which is rather 

 larger than the fixed end. 



Hal), ^larine, on hard objects. 



Loc. Atlantic Ocean, in 374 fathoms, a few miles north of 

 Cape St. Vincent ; on a fragment of Corallistes Bowerbankii, 

 Carter. 



Obs. There is only one specimen of this sponge; and it is 

 fixed to the fiat surface of one of the fragments of Coralliates 

 Boicerhnnkii in the large jar bearing the figures 374 fathoms, 

 = station 25 of the 1870 cruise. 



The spicular complement approaches nearest to that of the 

 group llalichondrina ; but I have never been able to find the 

 spined acuate spicule common to the sponges of this group, 

 except in one mounted instance, where it appears to be acci- 

 dental, as I have sought for it in vain in many other frag- 

 ments both of the dermal and internal structures. This again 

 is another of the " histodermal " sponges dredged up on board 

 the ' Porcupine.' 



Halichondria ahyssi ('Annals,' 1874, vol. xiv. p. 245, pi. xiv. 

 figs. 26-28). (PI. XIV. fig. 24, a, b.) 



Since desci-ibing and illustrating the fragment of this sponge 

 {I. c), Mr. T. Higgin of Huyton, near Liverpool, has brought 

 to my notice that the embryonic form {1. c. fig. 27, c) is birotu- 

 late — that is, that each end terminates in a dome-shaped or 

 umbrella-like head composed of twelve spines webbed together 

 (PI. XIV. fig. 24, b) like the birotulate of Ibjalonema &c. 

 That this spicule is still what I have termed it, viz. " embry- 

 onic," is proved by my having found that the fully developed 

 spicule (/. c. fig, 27, h) presents the same kind of head when a 

 favourable view can be obtained of it (which is rather difficult, 

 as the matured form generally lies on its side). The sh^ft, 

 too, is often evidently bent, even in the embryonic state. 

 Lately Mr. Iliggin has found a West-Indian sponge of a 

 pur])le-brown eolour charged with this embryonic form only, 

 which is identical with a fragment of the same kind of sponge 

 in the British Museum stated to have come from Blackwood 

 Bay in Australia. As the spicules of this species somewhat 

 differ from Halichondria ahyssi, Mr. Iliggin, who has now 



