PORIFERA. III. 



43 



of dermal spicules stretch, generally in a more or less oblique direction, from the interior of the sponge 

 out to the dermis; besides, they are also found in the dermis, below the layer of chelse, as scattered 

 bundles or single spicules; finally they form, as said, the skeleton of the oscular wall, also lying here 

 below the layer of chelae. The main skeleton is formed of the acanthostyli which all have the heads 

 fixed on the substratum and are vertical; the largest acanthostyli reach with the point up to the 

 dermal membrane, but in the undamaged sponges they scarcely project beyond it. The smaller styles 

 are placed between the larger. Spongin was not observed with certainty. 



Spiczila: a. Megasclera. i. The skeletal spicules are acanthostyli which are generally 

 straight, sometimes slightly curved; they have a somewhat distinct head, and from this they taper 

 evenly, thus forming a long apex which is often a little more abruptly pointed at the very point. 

 The spinulation is somewhat dense in the lower part of the spicule, but becomes more scattered out- 

 wards, and the outermost part is generally smooth; the longer the spicules are the point is to a 

 greater extent smooth, and in the smaller spicules the spines are found quite out to the point. The 

 spines are somewhat reclined. The head is densely covered with spines, which are considerably larger 

 than the others, and also have a different shape; they are not reclined but more or less straight 

 radiating, and they are as a rule not pointed but obtuse at the end; this obtuse or cut end is not 

 rarely somewhat jagged or crenulated. The styles vary much in size and as the intermediate forms 

 occur somewhat sparingly, the styles woiild seem divided into two groups with regard to size, but 

 there is certainly no principal division into two groups. The length varies in all between 0-09 and 

 '33 mm ) an d tli e diameter at the head, including the spines, varies from 0-014 0-035'""'. With regard 

 to the size of the styles there may be some difference in different individuals, in some the greatest 

 length was thus 0-33 mm and the diameter o'O24 ram ; when the spicules thus only reach a smaller length, 

 the mentioned division into two groups is generally still less distinct. 2. The dermal spicules are 

 rather slender, straight strongyla; the two ends are often a little different, one being slightly thicker 

 than the other, and sometimes one or both ends are slightly swollen; in other cases the ends are 

 somewhat narrowed. The strongyla are always polytylote with a row of swellings; this may be more 

 or less pronounced, but is rarely or never quite wanting. The strougyla have a length of 0-196 0-30"', 

 and a diameter in the middle of 0-005 0-007 mm . These spicules do not vary much in the various 

 individuals, b. Microsclcra; these are chelae arcuatae; they have a more or less, but always rather 

 strongly, curved shaft, the alae are lobe-shaped, the tooth is narrowly elliptical with the end rounded, 

 and there is a long, narrow tuberculum. The shaft is not cylindrical but somewhat flattened, which 

 may be present to a higher or lower degree. The chelse may vary a little in shape and size in the 

 various individuals, the shape, however, is chiefly the same. The length is, all variations concerned, 

 0-028 0-050"""; as instances of variation in size in various individuals I may note the following: 

 0-0280-038""", 0-0350-042""", 0-037 0-045 mm an d 0-032 0-050 mm ; the diameter of the shaft is 0-004 

 o-oio 1 " 1 " in relation to the size of the chela, and to whether it is seen in front or side view. As said, 

 the chela; occur in the dermal membrane forming a dense layer; they are also seen singly through 

 the whole body. 



Remarks: I have determined the above species as H. Kochleri Tops., but not without hesitation. 

 When Topsent in 1896 founded the species, he laid stress especially on the polytylote strongyles, 



