224 Mr. A. Newton on the Discovery of 



The methods by which I succeeded in rendering the young 

 Synapta accessible to observation, the details of the develop- 

 mental processes, so far as they have not already been observed 

 by J. Miiller, and the anatomical characters of Synapta digitata 

 (visible with remarkable facility in the little transparent creatures, 

 which are perfect from mouth to anus) shall be described in detail. 

 At the same time reasons will be given why the unveiling the 

 vital history of the molluskigerous sac is rendered probable by 

 the discovery of these young Synapta. The difficulties which 

 set bounds to the further prosecution of this course lie in the fact 

 that it was not possible to capture Synapta digitata in the young- 

 state described in the same quantity as the full-grown animals, 

 which is the first condition for the observation of the molluski- 

 gerous sac, on account of its great rarity. 



Together with Synapta digitata, the somewhat smaller Synapta 

 inharens (probably S. Duverncea, Quatref.), distinguished by its 

 more strongly adhesive skin and plumosely branched tentacles, 

 occurs in smaller numbers near Trieste, in the Bay of Muggia. 

 I had the opportunity of observing the brood of this species 

 also, mixed with that of S. digitata, up to the point at which it 

 likewise had the anchors in its skin and acquired the full 

 number and specific form of its tentacles. The young Holo- 

 thurids of this species are only distinguished by having no 

 calcareous wheels or globules in the posterior extremity, but, 

 instead of them, a group of irregularly angular calcareous pieces. 

 From the Auricularia of Synapta digitata that of S. inharens pro- 

 bably does not differ at all, except in this condition of the calca- 

 reous structure. The latter would, therefore, not be recognized 

 at the time when only larvae, without any young Holothurids, 

 occurred. 



XXIII. — On the Discovery of Ancient Remains of Emys lutaria 

 in Norfolk. By Alfred Newton, M.A., F.L.S. 



[Plates VI. & VII.] 



On the 31st of March last, in the course of a communication to 

 the Philosophical Society of the University of Cambridge, I had 

 the pleasure to announce a fact in British arch aeon tology, which, 

 as far as I am aware, is hitherto unrecorded ; and as that paper 

 will not be published in a form likely to bring it under the 

 especial notice of naturalists, I propose to give a short account 

 here of what I venture to think may be regarded as a discovery 

 not altogether unimportant. 



In the early part of this year, while examining a considerable 

 collection of ancient remains in the possession of Mr. Birch, of 



