306 THE VOYAGE OF H.M.S. CHALLENGER. 



the Aplirocallistidoe — which he placed in the order of the Corallispongia between 

 the families Dactylocalycid^ and Euplectellidse ; and he characterised it as follows: — 

 " Sponge tubular, tubes closed with a reticulate lid ; parietes formed of agglutinated 

 siliceous spicula, with round horizontal lateral pores ; inner surface strengthened with 

 clustered longitudinal bundles of elongated spicula." 



The generic diagnosis of Aphrocallistes ran thus : — " Sponge tubular, closed with a 

 lid, with smaller lateral tubular branches, which are generally open at the ends." The 

 remark contained in the first description given in 1858, to the effect that the skeleton of 

 Aphrocallistes beatrix is " calcareous," Gray now speaks of as a mere " slip of the pen," 

 and particularly notifies that it should have been called " siliceous." 



A figure of several of the forms of spicules, together with a portion of the reticulate 

 framework of siliceous beams belonging to Aphrocallistes beatrix, occurs in Wyville 

 Thomson's communication on the vitreous sponges,* where special attention is called to 

 the peculiar spicular form, " which consists of a lengthened shaft, ending in a small 

 expansion, from which spring four equal branches, each terminated by a little knob." 



In his paper on Holtenia,^ Wyville Thomson refers not only to Ap>hrocaU{stes 

 beatrix, Gray, but to a second species, Aphrocallistes bocagei, Wright MS. (p. 713). As 

 a very frequently occurring spicule of Aphrocallistes he describes a "regular six- 

 rayed star, with the principal axis longer than the transverse rays and one half of it 

 feathered." 



In 1869^ Bowerbank referred Aphrocallistes beatrix, Gray, to his genus Iphiteon, and 

 named it Iphiteon beatrix. This generic name — Iphiteon — Bowerbank has, it is true, 

 ascribed to Valenciennes, but upon no other ground, it would seem, than that he found 

 the form in the Museum of the Jardin des Plantes, Paris, noted on the labels as 

 Iphiteon panicea, Valenciennes. Bowerbank has characterised this genus by the following 

 diagnosis {loc. cit., -p. 76): — "Skeleton siliceo-fibrous, fibres solid, cylindrical, reticula- 

 tions symmetrical, areas rotulate, confluent." 



Perceval Wright has described and figured a second species of the same genus, under 

 the name of Aphrocallistes bocagei} Various specimens of this form, brought from the 

 Cape Verde Islands, were preserved in the Museum of Lisbon, in the British Museum, and 

 in his own collection, and had also been dredged by Wyville Thomson during the 

 " Porcupine " Expedition, off the south-west coast of Ireland, in deep water. The short 

 but clear description given by Wright runs as follows : — " Sj^onge fistulous, erect, 

 branching somewhat irregularly ; skeleton siliceo fibrous, more or less symmetrically 

 radial ; radii short and stout on the outer surface of the skeleton, forming a series of 

 hexagonal spaces, which are nearly all of the same dimensions, central umbo of the ray 

 giving origin on its inner surface, often on both surfaces, to a long spine. These spines, 



1 Ann. and Mag. Nat. Hist., ser. 4, vol. i. p. 123, 1868. ^ p/ij^. Trans., vol. clix. pp. 701-720. 



3 Proc. Zool. Soc. Land., p. 75. * Qiuirt. Jomii. Micr. Sci., January 1870, pp. 77-7S. 



