350 Air. R. Kirkpatrick on 



Placinolopha spinosa^ sp. n. (PI. XIII. fig. 2, a-m.) 



The specimen forms a whitish brown crust about 10 millim. 

 in area and 1-2 millim. thick, creeping over a nodule of 

 coralline. Several oval oscules, '5 x -25 millim. in diameter, 

 with membranous edges level with the surface, are present. 

 The choanosome forms more or less vertical folds beneath 

 the cctoscme. The skeleton is composed of micro-calthrops 

 of various sizes densely scattered in the ectosome and walls 

 of the choanosomal folds, and of lophodiactines arranged 

 tangential!}' in the ectosome and in the walls of the folds. 



Spicules. — Microcalthrops in graduated sizes, from very 

 slender forms with rays 24 x 2 /a, smooth or slightly spined, 

 with simple or bifid ends, up to stout forms with rays 42 x 9 /u., 

 much spined and di- or trichotomously branched at the ends. 

 Lophodiactines 2^10 X 12 /i, with simple or branched spines 

 aTid once or twice branched at the ends. 



The lophodiactines of F.spinosa resemble in form a spicule 

 figured by Sollas (26, jd. xxxv. fig. 24), who found it asso- 

 ciated with spicules of the Lithistid Coratlistes Thomasi from 

 the Ki Islands. Sollas, who was doubtful whether to regard 

 the spicule as Tctractinellid or Monaxonid, assigned it to a 

 new genus and species — Orthorhachis prublematica. It seems 

 very probable that Sollas's species comes under Placino- 

 lopha. The spicule figured by him is 450x40 /u., nearly 

 twice the size of the largest lophodiactine of P. spinosa. 



Including that of Sollas, there are three species belonging 

 to this genus : — 



P. Bedoti, Topsent.— Philippines (28, p. 429). 



P. {■ptnosa^ sp. n. — Funafuti. 



P. problernatica, Sollas. — Ki Islands. 



Locality. E. end of Fuafatu, Funafuti Atoll, 50-70 fath. 



Placinastrella clathrata, sp. n. (PI. XIII. fig. 3, a-o.) 



The specimen, which forms a small, rounded, soft nodule 

 8x5x5 millim. in size and of dirty white colour in spirit, 

 appears to have been cut off from a coral. 



The surface is smooth, but when highly magnified shows 

 an extremely fine pile formed by the points of a palisade of 

 cortical diactines. An oscule in the form of an irregular 

 fissure about 1 millim. in length, and level with the surface, 

 occurs on the summit of the specimen. The pores occupy 

 irregular cribriform areas with well-defined margins; the 

 sieve-meshes are 70 fj, in diameter and the pores about 30 /j, 

 (about two or three to a mesh). The pores lead by short 



