22 



piece is attached to the middle piece (c) so as to form with it a sort of hinge, which allows 

 of a very considerable mobility in a fixed direction. The side-pieces are continued forward 

 into the forceps, which exhibits a strong curvature inwards and has a kind of short cylindrical 

 neck, after which it is enlarged at the extremity almost in the form of a gouge. Along the 

 upper nearly straight truncated and sharp edge and a little way down on each side, the 

 extremity of the jaw of the forceps is armed with a row of pointed teeth bent inwards, of 

 which that situated at each corner is largest, (see fig. 30). When both jaws are curved to- 

 wards each other, (see fig 25 - 27) these teeth fit accurately between each other, and can 

 thereby hold the smallest objects fast. In like manner the above-mentioned vertical dentated 

 edges proceeding from the middle, meet in the middle line, while there always remains be- 

 tween these and the extremity of the forceps a considerable open space. Herein the pedicel- 

 larise in the Brisinga differ essentially from those of the genus Pedicellaster and Asterias, 

 where the forceps closes in its whole length. From each side-piece there issues downwards 

 a large plate-shaped process (b) directed obliquely inwards, yet not lying in the same axis 

 as the proper forceps, but forming with it an obtuse angle (see fig. 26). At the base this 

 process in somewhat instricted, and distinctly marked out from the rest of the side-piece 

 by a small sinus in the exterior edge, in which one extremity of the middle piece (c) fits. 

 Inside of the exterior convex border there are a certain number of larger and smaller oval 

 apertures which have a somewhat constant arrangement on all the pedicellarise. At the en- 

 larged plate-like extremity of this process there is attached an evident muscle (fig. 26 m) 

 the other end of which is inserted in the opposite similarly plate-formed part of the middle 

 piece (c). By the contraction of this muscle the jaws of the forceps are moved inwards 

 and towards each other, turning round the extremities of the middle piece as on a hinge. 

 When the muscle is relaxed, the jaws separate again from each other, whereby the side- 

 pieces are brought nearly into a horisontal position (see fig. 28). The middle piece (c) in- 

 serted between the two side-pieces and serving as an articulation for them, is much smaller; 

 it is situated transversally, and exhibits on the under-side 2 plate-shaped enlargements sepa- 

 rated by a deep sinus in the middle, and like the lower process of the side-pieces, perforated 

 with small apertures, which are usually arranged in a double row along the lower curved 

 edge. These plate-like enlargements, which serve for the insertion of the muscles that move 

 the jaws of the forceps, do not however lie exactly in the same plane, but have in relation 

 to the axis of the middle-piece a somewhat oblique position. Viewed from above (fig. 29 ( 

 this piece exhibits therefore a narrow nearly cross-like shape with its greatest width in the 

 middle, and the rapidly tapering ends, curved each to its side, partially embracing the side- 

 pieces in the middle. From the upper side there issue 2 short obtuse processes directed 

 obliquely outwards and leaning on each side against the inner vertical dentated edge; they 

 partially cover each other, when the middle piece is viewed from the broad side, and together 

 appear like an elevation in the middle of the upper edge, (see fig. 25, 27). 



