REPORT ON THE HEXACTINELLIDA. 301 



frequent occurrence are the medium-sized oxyhexasters with simple principal rays of 

 medium length, and with two to four outward bent medium-sized terminals (PI. LXXXI. 

 fig. 5). The terminal rays are usually twice as long as the principals which bear them. 

 In the second place and much more abundantly, sometimes indeed remarkably crowded, 

 are small discohexasters, with four to six simple or S-shaped, short, terminally knobbed 

 terminal rays on each of the simple medium-sized principals (PI. LXXXI. fig. 4). The 

 dermal and gastral peutacts are very like one another. Both the slightly incurved 

 tangentials and the radial ray projecting into the parenchyma are somewhat rough, and 

 end ill club-shaped, rounded, or more rarely sharpened swellings (PI. LXXXI. fig. 8). 

 The sixth ray is absent. Its position is either wholly unoccupied, or is marked only 

 by a gentle elevation. Besides the pentact hypodermalia, there are a great number 

 of dermal scopulse, usually pushed far forward, and are generally arranged in tufts on 

 each pentact. The shaft is rough, swollen into a club-shape at the lower end, somewhat 

 conically expanded above. It bears four rather markedly diverging terminal rays, 

 frequently bent somewhat outwards. Each terminal forms a club-shaped, often almost 

 spherical, and tolerably distinct terminal portion, which gives off laterally several 

 transverse rows of barbs, while the somewhat flattened terminal surface appears to be 

 smooth. The thin stalk of the terminal ray is beset with very minute pointed barbs, 

 which are also directed backwards. 



The gastral scopulse, which occur much more sparsely, have in general the same 

 structure. The terminal rays seem to be more slender, and their terminal knob is smaller 

 than in the dermal scopulse. 



In the character of its soft body, Periphragella elisie does not essentially differ from 

 Eurete. In the subdermal trabecula, in some regions, groups of small cells occur, which 

 I regard as immature sperm-balls. 



Genus 3. Lefroyella, Wyville Thomson (PI. LXXXIL). 



Lefroyella decora, Wyville Thomson. 



History. — In Wyville Thomson's preliminary account of a part of the voyage of the 

 Challenger Expedition, entitled The Atlantic, 1877, p. 401, we read : — " On the following 

 day we sounded in 2500 fathoms, and on the 29th in 1075 fathoms, in sight of the Ber- 

 mudas, with a bottom of coral mud. The dredge was put over and veered to 1600 fathoms. 

 It came up at noon with the pasty mortar-like lifeless contents which we find almost 

 constantly on the slopes of coral reefs ; the lime sediment was mixed with a large pro- 

 portion of the shells of Pteropods and Heteropods. Two fine specimens of a HexactineUid 

 sponge were hanging to the tangles, both unfortunately dead and slightly water worn. 

 The largest specimen, which seems to be nearly complete, is 170 mm. in height, and 

 shaped somewhat like an old fashioned tall champagne glass. It rests on a very solid 



