, PORIFERA. III. 



i. G. pyrula Cart. 

 PI. II, Figs. 15 — 19, PI. V, Fig. 2. 



1876. Conictella pyrula Carter, Ann. Mag. Nat. Hist. 4, XVIII, 388, PI. XIV, fig. 20, PI. XV, fig. 38. 

 1885. Sclerilla arctica Armauer Hansen, The Norwegian North Atl. Exp. XIII, Spongiadae, 12, PI. II, 



fig. 4, PL IV, fig. 15. 

 1885. Sclerilla dura Armauer Hansen, ibid. 13, PL II, fig. 5. 

 1892. Yvesia pedunculataTo^s&at, Resultats des camp. sc. du Prince de Monaco, Fasc. II, 105, PL V, fig. 6, 



PL X, fig. 17. 



1903. Yvesia lobata Arnesen, Bergens Mus. Aarb. 18, Taf. II, Fig. 7, Taf. V, Fig. 1, Taf. VI, Fig. 2. 



1904. Yvesia pertusa Topsent (non pertusa Tops. 1892), 1. c. Fasc. XXV, 196, PL XV, fig. 20. 

 1909. Grayclla pyrula, L,undbeck, Meddel. 0111 Gronland, XXIX, 443. 



Erect, club-shaped, generally with a shorter or longer peduncle, above sometimes divided into a 

 couple of branches, or somewhat lobate ; sometimes it may be compressed. Surface smooth, densely beset 

 with small, round or oval, more or less distinct pore-areas : the dermal membrane is stretched over the 

 pore-areas as a thin membrane, between these it is not sharply marked, resting on the ends of the fibres 

 of the main skeleton. The pores are found in the pore-areas; oscula spout-shaped, present in vary big 

 numbers on the upper part, or scattered. The dermal skeleton formed of close-lying, tangential acantho- 

 styli; the pore-areas have only cliche. The main skeleton consisting of a central axis from which fibres 

 radiate to the surface more or less regularly; there are no transverse fibres, but between the fibres lie 

 scattered acanthostyli. Spicula; megasclcra ; the skeletal spicules smooth tomota o-jtf — o-j6'""", the 

 dermal spicules acanthostyli crug — o-iq6" 1 " ' ; microsclcra chela arcuatce 0-021 — 0-0257""". 



Of this interesting species we have a somewhat considerable material of specimens of various 

 sizes. The species is always erect and more or less distinctly club-shaped, and the deviations which 

 may occur are easily traced back to the club-like shape. The small specimens are all regularlv club- 

 shaped with a shorter or longer peduncle; it is when the sponge grows larger that the shape may 

 vary somewhat, thus the upper part of the body may be thicker or thinner in relation to the peduncle, 

 the sponge may be high and slender or relatively short and thick, in the latter case it may be without 

 any pronounced peduncle, only narrowed below; further it may be divided into a couple of branches 

 in its upper part, or be more irregularly lobate, or finally it may instead of being round be rather 

 strongly compressed. All previously described specimens are small, and they all have also a club- 

 shaped exterior, only the specimen described by Armauer Hansen 1. c. is larger and shows the 

 branched and compressed shape. One of the smallest of my specimens has a height of u mm , the pe- 

 duncle is i'5 mm thick and the upper part about 5 mm thick; then we have specimens of all sizes up- 

 wards, the largest has a height of 5o mm of which the peduncle makes the half part; this latter, which 

 is rather thin, has a diameter of about 2 ram , and the upper part is about io mm in thickness. The 

 peduncle is slightly dilated below and shows here a surface of attachment, but most specimens are torn 

 from the substratum, a single one sits on a fragment of a mussel-shell. The consistency is rather 

 hard and somewhat elastic, but it may be different according to the degree of contraction; when the 

 sponge is strongly contracted, as is often the case, the consistency gets very hard. The colour (in 



