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Show 320 DR. J. S. BOWERBANK ON THE SPONGIADcE. [Mar. 18, matrix lining the canaliculi; spicula same as those of the skeleton. Dermal membrane pellucid, furnished with a unispiculous rete. Skeleton stout and strong ; primary and secondary lines both multispiculous ; spicula acerate, short and stout. Interstitial membranes pellucid, rarely spiculous ; spicula acerate, slender, few in number. Gemmules membranaceous, round or oval. Colour in the dried state light ochreous yellow, or pink in parts. Hab. East Indies (S. P. Pratt, Esq.). Examined in the dried state. I received this remarkable sponge, with several others, from my late friend S. P. Pratt, Esq., to whom they were sent by his son from the East Indies. No part of the basal portion remains by which we might have judged of its natural size. In its present condition its colour is light ochreous yellow, with patches of rose-colour or pink on some parts of its distal end; and this tint penetrates considerably below the dermal surface. In its present state it is very firm and strong. The inhalant system affords the most remarkable specific characters. It is elaborately constructed, and is unlike that of any other sponge with which I am acquainted. It consists of numerous pocilla, sunk beneath the dermal surface, each pocillum being covered by an elaborately constructed lid or shield, contained within a circular area or ring of closely packed spicula, from the inner margin of which are projected ten conical sacculi, their apices nearly meeting at the centre of the circular area. Many of these areas occur singly, slightly sunk beneath the dermal surface, while others are seen to be two, three, or more in linear arrangement, in short shallow canaliculi ; and in some cases ten or twelve are disposed in a long and frequently curved or sinuous canal. The canaliculi do not form a connected system : each, whether short or long, is unconnected with the adjoining ones. The canaliculi are all lined with a thin continuous bed or matrix, composed of closely felted spicula, of the same size and form as those of the skeleton, in which the inhalant organs are imbedded, and which connects them with the others in that linear series. All the canals terminate with an inhalant area; and I have never seen an instance of either the lining matrix or the canal extending beyond the terminal inhalant areas. The pocilla are nearly hemispherical; and the membranes of which they are constructed are abundantly strengthened by numerous spicula, of the same form and size as those of the skeleton, dispersed over the surface. The system of conical sacculi by which a pocillum is protected is also abundantly furnished with spicula, which are frequently projected from the apices of the cones into the open space between their terminations. The external surfaces of the conical sacculi are completely closed, and coated by closely packed spicula ; but the basal portions of their inner surfaces are, for nearly half their length, open, as represented in fig. 8, as if a slice had been taken from each near the middle of its length, in a diagonal direction towards its base; so that it would appear that the conical organs are impervious to the external water, which enters the hemispherical basin |
