96 REPORT — 1864. 



cellaria belonged to Urader glacialls, to Echinus sphcera, or to Ampliidotus com- 

 munis. Further, that although the general form of pedicellarise of Uraster ruhens 

 presents great similarity to those of U. (jlacialis, and tliose of Echinus miliuris agree 

 rem.arkably in character with those of E. lividus or E. sphcera, yet there are abun- 

 dant differences and peculiarities in their appearance to indicate to the practical 

 eye to what particular species it may belong. The author has hitherto found only 

 pedicellariaj in the genera Uraster, SpatanguSy Amphidotus, and Echinus, having 

 examined many other genera of Echinodermata for them ineffectually, more espe- 

 cially Comatula, Ophiocoma, and the Ophiuridfe. Amongst the family of the 

 j\.steriadiB, the genera Crihella, Palmipes, Solaster, Goniaster, Luidia, Aster ia, 

 and Asterina are apparently equally deficient in true pedicellarife. Amongst the 

 EchinidfG, the author has had no opportunity of examining Cidaris, Echino- 

 vi/amus, Echinarachnitts, or Amphidotus roseusj consequently he can give no definite 

 opinion on these genera or species ; but he thinks it probable that the latter at 

 least may possess these pedicellarial organs. The Holotliuriadag, together with the 

 otherCirrhovermigradeEchiuodermata, also want pedicellarite ; for it is here scarcely 

 necessary to remark, that the calcareous spicules and perforated plates existing in 

 these Echinoderms are the analogues of the pentagonal plates constituting the 

 shell of the Echini, whilst the oral tentacles are quite free from calcareous appen- 

 dages. In the genus Si/napta, the perforated plates and anchor-shaped appendages 

 may possiblj^ be thought to bear some nearer resemblance to pedicellarite ; but a 

 closer inspection of these peculiar bodies will convince lis that these perforated 

 plates are also the analogues of the pentagonal plates of an Echinus-shell, whilst 

 the anchors are merely nioditications of the spines, and are used as organs for pre- 

 hension or locomotion, and assist the animal in raising its vermiform body to the 

 mouth of its tube, the anchors being withdrawn during the period of contraction 

 of the Synapta, and contribute little or nothing to the powers of defending the 

 animal from the attacks of its predatory enemies. It will be seen that the pedi- 

 cellarife of the genus Uraster have been well illustrated in two individual species, 

 Uraster rubens and U. glacialis, and that they are very different in form from 

 those of the genera Spatangus, Amphidotus, and Echinus, all of which possess pedi- 

 cellarite consisting of three calcareous blades, while the Urasters have invariably 

 two blades in each pedicellarial head. Amongst the Echini, the species miliaris, 

 sphcera, Flemingii, lividus (two varieties), and neglectus have furnished numerous 

 illustrations, and an Echinus from the Mediterranean has also been examined, the 

 pedicellaria; of which were also so closely analogous in form to those of the Biitish 

 neglectus that the author was fully prepared to tind that a comparison of its other 

 characters -with those of that species would couhrm their identity ; and it subse- 

 quently did so without a.'oj possible doubt — an instance which may be considered 

 the strongest possiljle proof of the truth of the proposition, " that the forms of 

 the pedicellarise are peculiar to the species." 



All pedicellarife agree in having a calcareous framework of great beauty, con- 

 sisting of several pieces united together, and covered by a fleshy, sensitive, mus- 

 culo-membranous envelope, continuous with the common integument of the animal. 

 The pedicellariiTB on the genera Amphidotus, Spatangus, and Echinus possess, in 

 addition, a calcareous style or stem, which is also covered by a prolongation from 

 the skin or gelatinous envelope of the animal ; and the basal end of the style is 

 enlarged for articulation with a small knob or elevation upon the shell, adapted to 

 its reception in a ball-and-socket-like movement. Few objects are of greater 

 beauty than the pedicellarine of the Echinodermata, as the highly reticulated cha- 

 racter of the structure, the brilliant transparency of the ciystalline substance, and 

 sparkling gem-like elegance fully testify. But all these characters may be elicited 

 by ordinary examination in the microscope with transmitted, reflected, or oblique 

 rays falling upon them. Yet the highly doubly refracting properties of carbonate 

 of lime or Iceland spar, of which they are composed, make them still more lovely 

 objects when they are examined by polarized light and the selenite stage, but 

 without the analyzing crystal above the eye-piece : imder these circumstances the 

 pedicellarite themselves become their own analyzers by double refraction, and the 

 transparent colourless valve of pedicellarite becomes either red or gi-een, blue or 

 yellow, according to the thickne.?.? of the selenite plate beneath them. Some Echini, 



