620 COLLECTIONS FROM THE WESTERN INDIAN OCEAN. 



or sarcodic material, and a single form of spicule, viz. smooth 

 acuate of considerable length, and by the presence of a regular 

 dermal skeleton composed of spicules laid horizontally. I do not 

 know any other species except the original one, L. massalis, Carter, 

 and the two described below. 



42. Leucophlceus proteus. (Plate LIII. fig. B ; Plate LIV. 



%. *.) 



Massive, suberect ; irregularly columnar near base, showing a ten- 

 dency to terminato above in several short and thin membranous or 

 prismatic lobes, which by anastomosis inter se enclose cellular spaces, 

 within which the chief excretory canals open. Surface very variable 

 in character in different specimens ; either rough or even and 

 glabrous near the base, towards apex longitudinally ridged and 

 grooved, leading up into the membranous expansions just described, 

 and hispid with closely set, upwardly-directed sharp points, 1-2 

 millim. high, tending to coalesce into ridges, and terminated by 

 single projecting spicules. Vents opening either upwards at the 

 bottom of the spaces enclosed between the terminal lobes, or 

 laterally between the larger lateral ridges, 1-3 millim. in diameter. 

 Consistence in spirit — that of solid basal part firm, rather elastic, 

 that of upper laciniate parts compressible, elastic ; colour, surface 

 reddish purple, interior dull pale brown. Main skeleton formed of 

 very loose spicular tracts, 5-10 spicules broad, passing outwards from 

 the centre of the sponge, at distances of about -28 to "6 millim. from 

 each other, branching at acute angles, but maintaining a direction 

 subparallel to each other, and not crossing. No visible horny 

 uniting substance ; spicules connected by a yellowish sarcode, 

 rather darker than the interstitial sarcode. The terminal spicules 

 of the fibres either penetrate or support the dermal membrane. 

 Dermal skeleton consisting of irregular tracts of spicules laid obliquely 

 or vertically along the ends of the main-skeleton fibres. Sarcode 

 subtransparent, yellowish brown in centre, bright reddish purple at 

 surface. Spicules smooth acuate, bluntly rounded at base and 

 tapering gradually to sharp points from about the middle ; size about 

 2-5 by -032 millim. 



Hab. Providence Keef, Mascarene group, 24 fms. ; bottom, sand 

 and dead coral. 



Of the two spirit-specimens from which this description is drawn 

 up, the largest has the variable surface characters above described, 

 and must have been 50 millim. (2 inches) high by 2ii millim. 

 broad when perfect ; its basal portion is very irregularly formed, 

 being curved to one side and ending in a cup-shaped depression, by 

 which it was perhaps attached to a shell or other foreign body : 

 the smaller cpecimen has lost its base. The specific name, proteus, 

 is intended to commemorate the variability of the outward form. 



The general habit is that of L. massalis and fenestratus ; but the 

 spicules differ from those of the former in being about five times as 



