PORIFKRA. II. 205 



papilla; are whitish, the inside of the sponge is grayish white or quite white. The surface is slightly and 

 dispersedly shaggy. The dermal membrane is a rather thin, easily separable film, resting on the skeleton 

 below and provided with horizontal dermal spicules. Oscula: the papilla: described above are oscular 

 papillae; some of them are closed, others show a little opening at the apex of the cone. If a papilla 

 is cut off, a canal appears under it passing more or less perpendicularly into the sponge, which is 

 consequently set through with a number of more or less perpendicular canals. Pores were not seen. 



The skeleton. The dermal skeleton consists of dermal spicules, which are mostly horizontal and 

 irregularly scattered in the membrane; the membrane seems to be resting on the main skeleton below, 

 the spicules of which may project here and there. The dermal spicules, however, form also, here and 

 there, bundles passing from the skeleton below and supporting the membrane. In the walls of the 

 oscular papillae the dermal spicules are close-lying, all of them parallel to the longitudinal axis, and 

 thus forming a close spiculation in the wall. When the papilla is contracted and closed, the spicules 

 form a compact mass. The main skeleton is a quite irregular, partly polyspicular, partly unispicular 

 reticulation. Meshes are formed, but they are quite irregular. Fibres are only seen to a quite slight 

 degree, and, when found, they are only short and little marked. The spicules are united by a slight 

 amount of white and clear spongin. 



Spictila: a. JMcgasclera. 1. The skeletal spicules are styli; they are somewhat curved, the 

 curve is sometimes situated at the upper end, but sometimes they are more evenly curved, and they 

 may also be somewhat irregularly curved. They are in some degree fusiform , tapering distinctly 

 towards the upper end. The point is even and middle long. Their length is 0-62 — 074 mm , and the 

 thickness in the middle is 0'02i — 0'028 mm . Developmental forms occurred quite singly. 2. The dermal 

 spicules may most properly be called strongyla, but most frequently they have end-swellings so as 

 to approach tylota; they are somewhat fusiform. Their length is 0-357 — °'45'""\ anc ^ tne thickness 

 0-0114— o-oi5 mm ; sometimes they show a tendency to the polytylote form. In the fully developed 

 spicule the ends are equal; only few developmental forms were seen, showing that the spicules are 

 begun as monactinal. b. Microsclera ; these are of four forms, isochelae arcuatse, forcipes of two forms 

 and sizes, and sigmata. 1. The chelae arcuatse resemble the chelae in the preceding species, 

 F. fabric ans ; they have an evenly, sometimes rather highly curved shaft; the tooth is narrow, lanceo- 

 late, and has a short tuberculum, the alae are somewhat tooth-like and of about the same length as 

 the tooth. Their length is 0-034 — o-047 mm , and the thickness of the shaft is ca. 0-004— o-oo57 mm . 2 - The 

 large forcipes have two legs of equal length, ending in a small, button-like swelling; the curve may 

 be varying, it may be so strong, that the legs are parallel, and then it may be more and more slight, 

 until the legs form an obtuse angle; the forcipes are spined, and the spines are compressed and di- 

 rected backward. No serial arrangement of the spines is found here; the terminal knobs of the legs 

 are, as in F. Jabricans, indented or spined at the edge. Their length, measured from the curve and 

 to the end of one of the legs, is 0-086— o-i04 mm , and the thickness at the curve is 0-007 —o-oo8 mm . -^ 

 few developmental forms were seen; they are smooth, and the legs do not end in a swelling; they 

 reach a comparatively considerable thickness, o-oo4 mm at the curve, before they begin to get spines. 

 3. The small forcipes have about parallel legs, one of which is almost always somewhat longer 

 than the other; the legs end in a small, button-like swelling. These forcipes are spined in the same 



