PORIFERA. III. 



39 



Spicules : 



skeletal. dermal. microsclera. shape. 



1903. G. lobata Arnesen (ibid. 18, Taf. II, 



Fig. 7, Taf. V, Fig. i, Taf. VI, Fig. 2) 



( Yvesia) oxea styli chelae arcuatae club-shaped. 



1904. carnosaTops. (I.e. Fasc. XXV, 198, 



PI. XV, fig. 19) (Yvesia) tornota, oxea -f- massive. 



polytylote 



gelida mihi tornota, strongyla chelae arcuatae club-shaped. 



polytylote 



Of these species, four: G. arctica Arm. Hans., dura Arm. Hans., pedunculata Tops., and lobata 

 Arnesen, disappear as identical with G. pyrula Cart, as shown above, (the shape of the spicules of 

 these species is in the above list given as recorded by the authors); the total number of the species 

 belonging at present to Grayella is thxis twenty, of which two, G. armigera Bow. and membranacea 

 Arm. Hans, are doubtful. 



Cribrella hospitalis O. Schmidt (Grundziige einer Spongienf. des Atlant. Gebiet. 1870, 56, Taf. IV, 

 Fig. 12) was by Topsent (1. c. 1892, 103) taken to be an Yvesia, and I thought the same (The Danish 

 Ingolf Exp. VI, 2, 1905, 127); Topsent had also good reasons for his interpretation, but yet it seems 

 not to be correct, and there is every reason to take this species to be a Stylostichon, as I have de- 

 clared more particularly (Meddel. om Gronland, XXIX, 1909, 447). Schmidt also says nothing about 

 the arrangement of the oxea and the acanthostyli in this species, whereas he does so with regard to 

 his next species C. papillosa, and I think it rather sure, that Fristedt's and Carter's hospitalis 

 are identical with Schmidt's species, and that the species is thus a Stylostichon; the figure by Carter 

 (Ann. Mag. Nat. Hist. 4, XVIII, PL XIII, fig. 18) of the outer shape of the sponge also points in 

 this direction. 



Subfam. 2. Ectyoninae. 



Hymedesmia Bow. 



(Leptosia Topsent, 1892.) 



Incrusting and generally very thin forms ; sometimes, on account of the manner of growth, 

 assuming a massive appearance, but also then in reality incrusting. The surface generally simple, 

 sometimes with more or less developed papilla' to which oscula and pores are connected. The main 

 skeleton consists of vertical acanthostyli with their heads based on the substratum; it may be more or 

 less dense, sometimes rather diffuse and little developed. The dermal skeleton formed of bundles or 

 fibres of dermal spicules, which generally stretch from the main skeleton, or qiiite from the base, upwards 

 to the dermal membrane; it may be very differently developed, sometimes consisting of scattered bundles, 

 sometimes of relatively long fibres, and it is not rarely by far the most developed part of the skeleton. 

 The dermal membrane itself, which is supported by the oiitermost bundles of the dermal skeleton, may 

 be with or without horizontal spictdes; it is generally charged -with dense-lying chela, often so dense, 

 that they form a layer. At the base of the sponge there is a generally small amount of spongin, in 

 which the heads of the acanthostyli are imbedded. Spicula: megasclera: the skeletal spicules are acantho- 

 styli, the head is generally more or less szvollen; they always vary greatly in size, and are often divided 



