I2Q PORIFERA. III. 



is probably not so in the fresh state. The dermal membrane seems to be quite wanting in the speci- 

 mens, so that I can say nothing about it or about pores and oscula. 



The skeleton. The dermal skeleton; as the dermal membrane is quite or nearly quite wanting 

 I can say only little about the dermal skeleton; it seems to be of a construction like that found in 

 the preceding species and thus consists of bundles of spicules stretching from the main skeleton to 

 the dermal membrane. The main skeleton is quite of the common construction, the acanthostyli reach 

 to the surface and they project as said beyond it. A small amount of spongin is visible at the sub- 

 stratum around the heads of the acanthostyli. 



Spicula: a. Megasclera. i. The skeletal spicules are acanthostyli of a somewhat characteristic 

 shape; they have a head-swelling which is not large, but generally distinct, they taper evenly into 

 the apex, but the point is a little more abrupt. The largest styli have only spines below; the head 

 is beset with somewhat robust spines, and there are very small spines on the part just above the 

 head; the shorter the styli are the more spined they are and the smallest styli are spined near to the 

 point. The spines on the head are blunt, giving the head in the large styli a characteristic appear- 

 ance; the spines of the shaft are relatively largest in the small styli. The styli vary much in length, 

 but they are not divided into two distinct groups. The length is 0-12— o - 47 mm , and the diameter of 

 the head 0-017 — o-037 mm . The smallest styli are the most numerous. 2. The dermal spicules are 

 slender and straight, or very slightly curved tornota, they are of the same thickness in the whole 

 length; the ends generally form typical tornotal points, only sometimes the shape is less pronounced. 

 The length is 0-238— 0-31 mm and the diameter is 0-0028— 0-004 """• D - Microsclera; these are ancorse 

 spatuliferae of two forms and sizes, large and small; they are both very beautiful spicules. 1. The 

 large ancors have a very slightly curved shaft and five to six elliptical teeth at each end; there 

 are somewhat narrow alae on the shaft, reaching a little longer towards the middle than the teeth. 

 Sometimes the number of teeth at each end is not equal, but may be five at one and six at the other 

 end; also some irregularity may be found, and when there are six teeth, generally one or two are a 

 little smaller than the others. The length is 0-062 — 0-071 mm , and the diameter of the shaft is 0-004 — 

 0-007 m "\ 2 - The small ancorse have a shape somewhat similar to that of the large, but they have 

 eight to eleven teeth at each end; the number of teeth may also here be different at the two ends; 

 there are small alae on the shaft, but they are not directed to the sides but backwards, they are 

 thus not or almost not seen when the ancora is viewed from in front, and they are on the whole 

 difficult to see; from the fact that they are directed backwards they get a position similar to the falxes 

 of the teeth, and teeth seem in reality sometimes to be formed here, so that there is a circlet of teeth 

 all round; the construction recalling what is found in the ancorse of some of the Iotrochota species, 

 e. g. / rotulancora (The Danish Ingolf Exp. VI, 2, Porifera, Part. II, 191, PI. XVIII, fig. 6 c — e). The 

 length is 0-032— 0-038 mm , and the thickness of the shaft 0-003 ram . Of this ancora some developmental 

 stages were seen; they showed a dilatation with beginning teeth at each end, and they thus resemble 

 the developmental stages of the ancora in the mentioned Iotrochota species. The microsclera occur in 

 the tissue of the sponge, and to judge from a single place on one of the specimens they also occur 

 in the dermal membrane in somewhat great numbers; the small ancorse are by far the most 

 numerous. 



