PORIFERA. II. 



I( 35 



consisting of closely and irregularly arranged spicules of a special form, besides being interwoven with 

 the common axial styli. It might be said that it was the outer part of the crusty layer, which was 

 interwoven with the special spicules, but then it must be remembered that the coating layer may 

 easily be removed as a separate layer. In the axis a rather copious, yellowish mass of spoil gin is 

 found cementing the needles of the single fibres and coating these fibres with a thin layer; on the 

 other hand, the fibres are not, or only to a slight degree, united by spongin, and they seem chiefly 

 to be held together by anastomoses passing very obliquely from one fibre to another. In the skeleton 

 outside the axes no spongin was observed. 



Spicula: a. Megasclcra are styli, dividing into two 

 forms, which, however, are not sharply separated: long, 

 straight styli chiefly forming the axes, both the central 

 one and those of the papillae, and shorter, most frequently 

 evenly curved styli found in the other parts of the body. 

 The long styli are straight or sometimes slightly and a 

 little irregularly curved; the}- taper a trifle from the middle 

 outward; at the rounded end there is a more sudden 

 tapering, the point is short and oftenest stubby. The 

 length reaches 2 mm , and may go down to ca. i-2 mm , and the 

 thickness is 0-03 down to ca. croi7 mm . The short styli are 

 almost always slightly and regularly curved; they have 

 likewise a sudden tapering at the upper end; the point 

 is somewhat longer than in the long ones, and it is gener- 

 ally sharp. The length is 0'56 mm up to ca. r2 mm , and the 

 thickness is in proportion 0011— o-024 mm . Thus the short 

 styli, while having a length like the shortest ones of the 

 long styli, are of greater thickness; as before mentioned, 

 however, the two groups are not sharply separated; neither 

 are they so with regard to their occurrence, some of the 

 shorter needles being found in the axis, while long needles 

 may be found in the other parts of the bod}-, only, how- 

 ever, in rather small numbers. Of both forms quite fine 



developmental forms are found, but only in small numbers. The spicules of the coating layer of the 

 stalk are curved, often somewhat irregularly curved, styli; the head-end shows often an inconsiderable, 

 scarcely perceptible swelling which is often placed a little below the end; they taper more or less 

 towards the opposite end, which is more or less broadly rounded. They are finely spinulous, so finely 

 that it is seen at most as a slight granulation, when the needle is not seen under very high magni- 

 fying powers. The length varies from cruS— o-34 mm , and the thickness at the upper end is about 

 0-0015 — o-oo4 mm ; there is no fixed proportion between the length and thickness, b. Microsclera ; these 

 are isancorse unguiferse of two forms and sigmata. 1. The ancorse of the large form have an 

 evenly curved shaft and six lanceolate teeth at either end. At either end are also found two narrow 



The Ingolf-Expedition VI. 2. j , 





Fig. 7. Chondrocladia gigantea Arm. Hans. 

 Longitudinal section through the end of a papilla 

 with a cavity in the outer end. Outermost the 

 crusty layer is found, then the softer tissue with 

 fewer spicules and in the middle the axis. A few 

 canals are seen, x 10. 



