21 



y. The Pedicellariie. 



These organs, which are very characteristic of the proper star-fishes, and which are 

 entirely wanting in the brittle stars or Ophiurse, appear in the Brisinga in the greatest 

 abundance, as well on the disc as on the arms. They are observed in quite enormous masses 

 in the cuticular sheath of all the furrow-spines and marginal spines, giving to it, as it were, a 

 granulated appearance; likewise in extraordinary abundance on the soft cuticular ridges which 

 surround the dorsal side of the arms in their whole length; they are observed in much 

 smaller numbers also, distributed over the remaining part of the skin, and on and between 

 the dorsal spines of the disc, (see Tab. 1, fig. 8 a). 



They are in the present species of Brisinga extremely small, scarcely more than 

 Vio 1 "" 1 long, and exhibit a remarkably complicated structure. Of all the known forms of 

 pedicellaria} they seem in their structure to resemble most those described by my Father 

 in the genus Pedicellaster; and, like them, belong to the principal form designated by 

 Job. Muller with the denomination Pedicellarise forcipatae, characterised by 2 pincer-like 

 branches provided with teeth that fit to each other and enabled by means of a peculiar 

 muscular apparatus to move towards each other, and thereby to grasp and to hold small 

 objects. 



On each pedicellaria there may be distinguished (see Tab. IV, fig. 23 & 24) a thicker 

 exterior part or capitulum, and a much thinner flexible stem whereby the pedicellaria is 

 attached to the skin. The exterior enlarged part which represents the proper body of the 

 pedicellaria, exhibits usually an oval form with the greatest thickness at the base, and the 

 extremity laterally somewhat compressed. On closer examination this part appears to con- 

 sist of 2 broad more or less gaping lobes, each of which envelopes the extremity of one of 

 the jaws of the forceps; the dentated edges here advancing freely from the fleshy envelope, 

 so as to work directly against each other. If a diluted solution of potass be applied to 

 such an isolated pedicellaria, whereby the exterior cuticular sheath will be rendered trans- 

 parent, the calcareous pieces which form the foundation of the pedicellaria will be seen very 

 distinctly inside the sheath in the upper enlarged part or capitulum; these calcareous pieces 

 (see fig. 25 — 29) are always 3 in number, namely 2 uniform side-pieces (a) which represent 

 the 2 movable jaws, and a 3 Ml unpaired calcareous piece (c), which is inserted between them 

 and serves both as articulation for the side pieces and attachment for the muscles (m) that 

 move them. All 3 calcareous pieces are hyaline and more or less perforated with small 

 circular or oval apertures. The side pieces (a) are thickest in the middle, and have in that 

 part on the inside a vertical dentated edge, which, when the jaws of the forceps are bent 

 towards each other, meets the corresponding edge on the other side-piece. On the pedi- 

 cellariae of the arms (fig. 27—29) this edge is quite short and evenly rounded, while on the 

 pedicellaria; of the disc (fig. 25, 26) it is considerably longer, quite straight, and projecting 

 at the anterior extremity in a short lobe. Immediately below this dentated edge, the side 



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