Sponges from Funafuti. 351 



canaliculi info a system of subderiDal spaces, which open into 

 incuncnt channels and spaces ir\ the interstices of a close 

 network of tubes, the lumen of the tubes constituting the 

 excurreiit canal system ; this arrangement recalls that found 

 in the Ascon p^enus Clalhrina. 



Skeleton. — The ectosome is supported by a palisudo of 

 slender diactines, but in the meshes of the pore-areas the 

 diactines are tangential. The walls of the choanosomal tubes 

 are supj)oited by tangentially arranged diactines, trijds, and 

 niicrocaltlno[>s of various sizes. 



Spicules. — Diactines attaining 1-40 X 5 /x, straight or slightly 

 curved, with a slight kink or irregular thickening in the centre, 

 and often abruptly bent near each end. Ectosomal diactines 

 36 X lo fi, with a slight kink in the centre. 



Triods regular or irregular, with two rays (together 

 120x4 /i) in a line and a shorter third ray (36 /x) forming an 

 angle. 



Oalthrops, larger forms with rays 36 x 5 /a, smaller with 

 rays 18 X 3 //,. 



The only other species of this gtnns Placinaitrellxc piosa, 

 Schuize (24, p. 433, pi. xxi. figs. 17-21), is found at Naples, 

 A cortical palisade of diactines is present in botJj ; but the 

 large definitely orientated oalthrops occurring in P. copiost, 

 are wanting in P. clathrata. 



The tubular reticulum appears to be merely an elaboration 

 of the system of simple folds found in Piaciaa simplex, an 1 

 the proper position for Placinastrelli is prob.ibly in the 

 family Placinida^, where JSchulze placed it (24, p. 44!)), rather 

 than in the Pachastrellidai, to which the genus was assigned 

 by Sollas {-IQ, p. 103). 



Locality. Funafuti Islet. 



Erylus monticularisy sp. n. (PI. XIV. fig. 3, a-h.) 



The sponge forms an extremely thin pale brown lamella 

 incrusting an Agaricia. Several minute conical oscules, 

 •07 niillim. in height and "175 millim. broad at the base, are 

 scattered over the tiat surface, tiie walls of the cones being 

 supported by a sloping palisade of small oxea 80 x 3 /x.. 



Skeleton. — Beneath the surtace-layer of disciform sterrasters 

 is a layer of scattered ortiiotriienes, with reduced rhabdomes 

 directed vertically downwards. 



Spicules. — Megascleres : oxea (few) slightly curved, 2LUx 

 10 /i. 



Orthotrijenes : rays of cladome each 186x3 /x, slender, 

 straight, sharp-pointed, rliab lome 6 /*. 



Microscleres : sterra.-^ters oval, with diameters 150 x 1 1 4 /*, 



