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PORIFERA. II. 



shaft; the ake are most frequently a little longer than the teeth. The teeth are directed slightly out- 

 ward. The length varies altogether between ca. 0-038 and o-07i mm ; it ma)' vary somewhat in the single 

 individual, not, however, so much. Thus in a specimen with the smallest ancorse the greatest length 

 was o-043' nm , and in a specimen with large ancorse the smallest form was o-059™ m long. The greatest 

 breadth of the ancorse from one lateral tooth to the other is about 0-014— o-025 mm . Besides the length 

 also the dimensions of the different parts may vary; thus alse and tooth may be comparatively longer 

 or shorter, and the free middle part of the shaft may, according to this variation, be from one third 

 to one fifth of the whole length. Of this ancora a few half-developed stages were seen, in which only 

 beginnings of the teeth and fakes were present. — This ancora showed frequently, at all events in 

 many individuals, many different deformities. It has been mentioned that the ancorse may vary some- 

 what with regard to the length of the teeth; also the breadth of the teeth may vary, and they may 

 be very narrow. Then they may be straight cut off at the end, and here they have very often an 

 incision, so that they become more or less deeply split. Further the alse may separate more or less 

 from the shaft, and each form a tooth, or they may coalesce so as to form one tooth, so that we 

 get four or five teeth, each directed its own way. The teeth or tooth-like structures which in the 

 mentioned cases replace the alse, appear, as far as I have been able to observe, when they are quite 

 separated from the shaft, to be upon the whole of the same construction as the genuine teeth, but 

 this is only rarely the case, as most frequently the)- are only partly separated from the shaft. All these 

 deformities, for as such they must be regarded, show the peculiarity that they are always symmetrical, 

 occurring in quite the same way in both ends. Finally the ancorse are often somewhat twisted. 2. The 

 small ancorse have a comparatively more curved shaft than the large ones, and further the teeth 

 are less directed forward, so that a line through the two middle teeth would be straight or almost 

 straight. In either end there are three leaf-shaped teeth, which are most narrow at the base, and an 

 ala on either side of the shaft. Teeth and alse are comparatively long, so that the ends of the teeth 

 approach each other, and the free middle part of the shaft is quite short, only ca. one eighth of the 

 whole length, so that there is often only seen an incision between the alse. The length of these 

 ancorse varies from 0-017 — o-o28 m,n , but the dimensions of the different parts remain about the same. 

 The breadth is ca. 0-0057 — o-oo85 mm . Also of this ancora a few developmental forms were seen. The 

 two forms of ancorse are sharply separated, both by their sizes and by the characteristic form of the 

 small ancora. A few ancorse may be found, however, that seem with regard to form and size to be 

 intermediate between the two groups, yet with regard to form the)' approach always more nearly to 

 the large ones. 3. Sigmata are more or less contort, up to one fourth of a turning. They are 

 exceedingly varying in length, from 0-024— o-075 rom . The variation, however, is not so great in all 

 individuals; thus the upper limit was measured in some specimens to o-o64 mm , and in others to only 

 o-04 mm , the lower limit, on the other hand, seems to be about the same. The thickness varies alto- 

 gether from o-ooi— o-O05 mm , according to the size. The middle sizes of the sigmata occur very sparingly, 

 and therefore the impression is frequently imparted that sigmata form two groups; this fact is espe- 

 cially conspicuous in the individuals in which sigmata reach the largest size, while the difference is 

 smaller in individuals in which sigmata do not reach any considerable size. When they are divided 

 in two groups, the fact is that the small sigmata may only vary a little in size, while the large ones 



