PORIFERA. II. 



*39 



elastic. The colour (in spirit) is in some specimens whitish yellow to grayish yellow, but not rarely 

 it is light brown or reddish brown. Lieberkiihn states that the fresh sponge is of a dirt}' rose-red 

 colour, and Schmidt says that it is yellowish or dirtily rose-red. The surface is much and irregularly 

 grooved, being, as in the preceding species, provided with knobs or sinuous ridges separating inter- 

 jacent grooves; otherwise it is quite slightly shaggy from projecting spicules. The dermal membrane 

 is a thin film supported by projecting bundles of dermal spicules spread in a penicillate way; other- 

 wise it has no skeleton. The pores are situated in the areas formed by the dermal skeleton; they are 

 especiallv close-lying over the larger subdermal cavities, where they most frequently reduce the mem- 

 brane to a network. They are round or oval, and their size is o - oi8 — o - ii' mn . Distinct oscula were not seen. 



The skeleton. The dermal skeleton consists, as in the preceding species, of bundles of tornota 

 which project from the main skeleton, being spread in a penicillate way, and support and pierce the 

 dermal membrane. The bundles have generally a length of only about one spicule; only where large 

 subdermal cavities are found, short fibres are formed of the tornota, which fibres pass into the mem- 

 brane stretched over the cavity, and branch, continually sending fan-shaped bundles up through the 

 membrane. The bundles are most frequently rather erect, but may in places be more or less recumbent. 

 Besides in the dermal skeleton tornota are also found in the membranes of, at all events, the larger 

 canals. The main skeleton is a rather irregular, polyspicular network. It forms partly tetrahedral, 

 partly more or less cubic or quite irregular meshes. Some longer fibres are found, especially running 

 towards the surface. In the mentioned free branches rather long fibres are formed running lengthways 

 of the branches. The fibres or spicula-bundles may have up to ca. six spicules alongside. As in the 

 preceding species spongin is found in the nodes of the skeleton, but it is only to be observed with 

 difficult}-, as it is only present in small amount, and is quite white and clear. 



Spicula: a. Megasclera. i. The skeletal spicules are acanthostyli, the}' are most frequently 

 slightly and evenly curved throughout their length, only more rarely they are straight; the point is 

 even and middle long, but may vary a little in length. The spines are much scattered and rather 

 small; only at the upper end the}' are a little more close-set, and are also here a little larger; the 

 point is smooth for a longer or shorter space. The length varies from 0-178 — o - 24 mm , and the thickness 

 from 0-008 — d-oii"" 11 . Some developmental forms were found, they were of different thickness, the finest 

 ones were measured to ca. 0'0007 mm , and had a length of about cri4 mm . Forms of a thickness of about 

 Q.QQjmm -were slightly knotty or almost smooth, whereas forms a little thicker were distinctly spined. 

 The developmental forms show a little distinct head-swelling, which is more distinct, the finer the 

 needle is. 2. The dermal spicules are tornota; they are straight or slightly curved in different 

 ways and slightly fusiform. Their ends are peculiarly formed; they taper only a little, and then they 

 are abruptly cut off, the edge of the end thus cut off carries some small points, most frequently, as 

 far as was to be seen, to a number of three. Sometimes the outer part of the tornote is quite slightly 

 swollen. Most frequently their ends are not quite equal, one being a little thinner than the other. 

 Their length varies from 0-178 — o-22 mm , and the thickness from 0004— o-oo8 mm . Developmental forms 

 were seen in small numbers; in conformity to the development they show the greater difference 

 between the two ends, the younger they are. b. Microsclera are of two forms, tridentate isancorse 

 unguiferae and sigmata. 1. The an cor a? have an evenly curved shaft; at either end they have three 



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