Sponges from the Atlantic Ocean. 213 



come from an ordinary form of the anchorate. Aims, as they 

 approach each other, becoming compressed, widened, and 

 knife-shaped, with the tliin edge inwards, and presenting, in 

 their fully developed state, fine parallel stria3 close together on 

 the blade, which are perpendicular to its curved outer margin 

 (fig. 9,i) ; also presenting, before the union of the arms is 

 completed, a notch on the inner edge (fig. 9, a), which is filled 

 up at maturity, at which time the shaft becomes undistinguish- 

 able from the arms : average largest size of melon-shaped 

 form 12 by 7-6000ths of an inch in its greatest diameters 

 (fig. 9) ; that of the embryonic form 6-6000ths inch long 

 (fig. 12). Size of entire specimen about 1\ inch in diameter 

 in all directions ; that of the tubercle about 1 to 2-6000ths 

 inch in diameter. 



Hah. Deep sea. 



Loc. Atlantic Ocean, between the north coast of Scotland 

 and the Faroe Islands. 



Obs. This specimen is alone ; and the label on the jar only 

 bears " Porcupine, 1869," which refers to the " voyage." It is 

 remarkable for the form of the full-grown anchorate, Avhich 

 here also, but for the presence of all minor grades of develop- 

 ment leading up to the matured one, could hardly have been 

 understood. It is further remarkable for the general form and 

 structure of the body, although the presence of a stiff, bladder- 

 like envelope or dermis, similarly composed and filled with a 

 soft, parenchymatous, fibreless mass does not, as we shall see 

 hereafter in Histoderma ajjpendiculatum, appear to be so much 

 confined to any particular species as to be a peculiarity of some 

 of the deep-sea sponges. It had grown on, and subsequently 

 partly round, the pebble at its base (PI. XIII. figs. 6 & 7, 5 h)^ 

 which, in the otherwise unattached state of the sponge, must 

 at once have served to keep it more or less stationary, with 

 the same side always uppermost. Hence, probably, the re- 

 stricted position of the pore-area. 



The alliance of the double form of skeleton-spicules here, as 

 well as their shape respectively, with those of Halichondria 

 mcrustans, would seem to indicate that this sponge should be 

 placed under the heading " Halichondrice " in my 5th division 

 of sponges, viz. Rayneri^. 



Esperia vilhsay n. gen. et sp. PI, XIII. figs. 13-15, and 

 PI. XV. fig. 36. 



General form massive, lobular, erect (fig. 13), growing from 

 a contracted portion of stout, naked fibre (fig. 13, a), whose main 

 filaments, being expanded at the ends, appear to have been torn 



