786 NEW GENERA OP MONAXONID SPONGES, 



parent; and the dermal pores (described as round or oval open- 

 ings about 70 to 10''^ in diameter) are very abundant on the 

 surface which bears the oscula ("occurring in small groups over 

 the ends of the inhalant canals, where they reduce the dermal 

 membrane to a mere network"), but are extremely scarce or 

 absent on the opposite side of the sponge. In the specimens 

 upon which the present description is based, — four in number 

 and, with one exception, in a dried state of preservation, — the 

 dermal membrane is wanting, and the surface opposite to that 

 » on which the oscula occur is closely dotted with numerous pin- 

 hole-like perforations, — only slightly smaller in diameter than 

 the oscula themselves, — which are the openings of the inhalant 

 canals: as a consequence the dry specimens, when held between 

 the eye and the light, present a minutely perforate appear- 

 ance. Also clearly visible, when the sponge is thus examined, 

 are stout, branching veins radiating upwards through the frond, 

 from stalk to margin, at a distance apart varying from about 5 

 to 10mm. On careful desarcodisation of the sponge by means 

 of caustic potash the skeleton is obtainable intact, and the 

 "veins" are then very conspicuous — appearing as stout, spong- 

 inous, dark yellowish or brownish-coloured fibres (PI. xl., fig. 1) ; 

 whereas the rest of the skeleton, owing to its extreme deficiency 

 in spongin-cement, appears almost pure white. The colour of 

 the sponge in alcohol is greyish yellow, and the consistency 

 rather soft and brittle; dry specimens are crisp to the touch, 

 inelastic, and very easily crushed. 



Skeleton. — Exclusive of the very few stout spiculo-spongin 

 fibres forming the "veins" above referred to, the skeleton (PI. 

 xxxix., figs. 1, 2) consists of pauciserial lines of (smooth stylote) 

 spicules — or, strictly speaking, spicule-fibres extremely scantily 

 provided with spongin, — united together, for the most part, by 

 single transverse spicules entirely free from spongin except at 

 their extremities. Not infrequently, however, the distance be- 

 tween adjoining spicule-fibres is greater than (sometimes nearly 

 as much as twice) a spicule's length and the interconnecting 

 spicules then form between them an irregular unispicular mesh- 

 work. In either case the connecting spicules are very numerous, 

 and are inclined to the direction of the fibres at very varying 

 angles ; and always a small proportion of them — through failure 

 to effect connection apically — appear simply to project from the 

 fibres in the manner of echinating spicules. The spicules form- 



