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



(l) Dacti/localyx piimiceus, Stutchbury, named Dactylocalyx jjumicea by Gray, and 

 identified with Iphiteon 2)cinicea, Valenciennes (Paris Museum), as a " sponge broad 

 expanded, upper surface rather concave. Hab. West Indies, Barbados, St. Vincent ; " ' 

 and (2) Dactylocalyx subglobosus, Gray, a " sponge subglobose, with a deep central 

 concavity above ; the outer surface with irregular anastomosing oscules. Hab. 

 Malacca (?)" (pi. xxvii. fig. 1). 



A short account of the nature of the continuous siliceous framework of Dactylocalyx 

 was given by Glaus in 1868 in his treatise on EuplecteUa aspergillum. He says on page 

 23 : — " We have thus to deal here not with united siliceous spicules, but with a fibrous 

 tress-work of siliceous substance like the ceratose fibrous networks which occur in the 

 Ceratospongia." On the other hand, Wyville Thomson in the same year remarks,- — " I 

 believe that it would be safe to accept the generalisation that the continuous siliceous 

 network, wherever it occurs in the vitreous sponges, is produced by the fusion of spicules 

 of the hexradiate type." 



A detailed description of all these sponges which Bowerbank ascribed to the genus 

 Dactylocalyx, Stutchbury, was given by the same author in 1869.^ After first separating 

 oflF the genus Iphiteon, Valenciennes, from Dactylocalyx, he characterised the genus 

 Dactylocalyx, Stutchbury, in the following manner: — Skeleton siliceo-fibrous, fibres solid, 

 cylindrical." Iphiteon, on the other hand, thus : — " Skeleton siliceo-fibrous, fibres solid, 

 cylindrical. Eeticulations symmetrical. Areas rotulate, confluent." 



To Dactylocalyx he ascribed the following, in part, newly described species : — 

 (1) Dactylocalyx pumiceus, Stutchbury ; (2) Dactylocalyx heteroformis, Bow^erbank ; 

 (3) Dactylocalyx macandrewii, Bowerbank ; (4) Dactylocalyx prattii, Bowerbank ; 

 (5) Dactylocalyx masonis, Bowerbank ; (6) Dactylocalyx howerhanhi, Johnson ; (7) 

 Dactylocalyx polydisctis, Bowerbank. Of all these, however, only the first, according 

 to the figures and descriptions, namely, Dactylocalyx pumiceus, Stutchbury, is truly a 

 Hexactinellid, all the others being Lithistida or Tetractinellida. 



From Bowerbank's long description of Dactylocalyx pumiceus, Stutchbury, I shall 

 quote only the diagnosis : — " Sponge cyathiform, slightly pedicelled, surface even. 

 Oscula and pores unknown. Expansile dermal system, connecting spicula furcated 

 attenuato-patento-ternate, and dichotomo-patento-ternate. Dermal membrane — tension 

 spicula small, acerate and subequiangular triradiate spicula ; retentive and defensive 

 spicula acerate or cylindrical verticil! ately spinous, whorls of spines numerous and very 

 large ; and also attenuato - stellate, very minute and numerous. Skeleton : — rete 

 irregular ; fibre stout, irregularly and abundantly tuberculated, apices of the tubercles 

 mainly papillous. Auxiliary skeleton-fibres more or less rectangular, hexradiate, 

 profusely spinous, distal terminations clavate, large and numerous. Tension spicula 



' Figured he. cit, pL ixvii-. fig. 2. - Ann and Mag. Nat. Hist., ser. 4, vol. i. p. 122. 



2 Proc. Zool. Soc. Loud., 1869, p. 76. 



