EEPORT ON THE MONAXONIDA. 133 



(PI. XXX. fig. 3, e), wliich proves to be a new species, cliaracterised by remarkably fiue 

 microsclera ; it will be found described on p. 84 under the name Esperiopsis 

 pulchella. 



The spination of the styli appears to be a very inconstant character in this species 

 {vide infra), and it is doubtful whether it is of even specific value ; nevertheless we have 

 made use of the fact that these spicules may be spined in selecting a name for the species. 

 This consideration tends to throw considerable doubt on the correctness of separating 

 genera, e.g., Tedania and Trachytedania, on this character alone. 



Xoca^%.— Station 192, September 26, 1874; lat. 5° 49' 15" S., long. 132° 14' 15" E.; 

 Little Ki Island, New Guinea; depth, 140 fathoms ; bottom, blue mud. One specimen. 



A second specimen in the collection is probably a slight variety of the above. It is, 

 however, a mere fragment, but it comes from the same station. The spiculation is as 

 follows: — (a) Megasdera; (l) large, smooth styli, with fairly sharp points (seldom or 

 never showing spination); measuring about 077 hj 0'028 mm.; (2) tylota, with very well 

 developed, oval heads; measuring about 0'42 by 0'0078 mm. {h) Microsclera; (l) 

 tridentate isochelse, with slightly curved shaft; length about 0'063 mm.; (2) large, 

 slender, simple (very rarely contort) sigmata, up to about 0'145 mm. in length. 



Myxilla mollis, Ridley and Dendy (PI. XXVII. figs. 4, 4«, 45). 



1886. Mijxilla mollis, Ridley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. p. 471. 



Sponge massive, amorphous. Largest sjaecimen about 62 mm. long by 31 mm. 

 broad and 12 to 19 mm. thick. Colour in spirit pale, creamy yellow. Texture 

 uniform throughout, very soft and spongy. Surface usually very uneven, but smooth. 

 Dermal membrane distinct, thin, transparent. Oscula scattered, having their margins 

 flush with the surface of the sponge. Pores scattered (?). 



Skeleton. — (a) Dermal ; composed of loosely scattered tylote spicules, together with 

 a certain proportion of styli ; sometimes forming a very irregular reticulation, in which 

 occasionally several spicules are found lying side by side, parallel with one another. 

 (6) Main; as loose and irregular as the dermal layer, consisting of a very indefinite 

 reticulation of stylote or subtylostylote spicules. 



Spicules. — (a) Megasdera; of two kinds. (1) Smooth sulitylostyli or styli (PI. XXVII. 

 fig. 4); these form the main skeleton and are generally subtylostylote, being more or less 

 enlarged at the base, and tapering more or less gradually to a sharp point at the apex ; 

 size about 0-42 by 0-01 mm.; (2) tylota (PI. XXVII. fig. 4a), each with a straight, slender 

 shaft and a distinct oval head at each end ; entirely smooth ; measuring about 0'22 by 

 0"006 mm. ; occurring abundantly in the dermal layer of the skeleton, (b) Microsclera; 

 (l) tridentate isochelaa (PI. XXVII. fig. Ab), with slightly curved shaft which, towards 

 the two ends, often appears to be expanded on each side into a slight fimbria ; length 



