958 RECORD OF CURRENT RESEARCHES RELATING TO 



appear to be all kinds of grades between distinct vessels with complete 

 walls, and those whicb may almost be regarded as lacunae. More- 

 over, there are examples of central vessels which give rise to largely 

 anastomosing peripheral branches ; and these (as in Leuckartia) may 

 even penetrate into the meshes of the fundamental tissue. Injections 

 might, of course, give rise to the appearance of vessels in cases such 

 as these. The author further directs attention to the great develop- 

 ment of the marginal fold of each joint in Solenophorus. 



Histolog'y of the Tetrarhynchi* — Herr Laczko says of the 

 " knobs " of the proboscis of these forms that they are provided with 

 two muscular layers. One is very thick on its outer surface, and 

 forms a layer of longitudinal fibres, arranged in three groups. The 

 other, external to this, consists of a double layer of diagonal fibres. 

 In addition to these, there is also a circular layer, the fibres of which 

 are thick. The retractor proboscidis arises independently from the 

 most posterior portion of the wall of the knob, and gradually decreases 

 in width as it passes forwards. The nervous system appears to be 

 exceedingly well-developed. On both the ventral and the dorsal sides 

 there is a well-developed layer of ganglionic cells. These are uni- 

 polar, of considerable size, and provided with a distinct nucleus. 

 The processes which arise from them, and which may be twice or 

 thrice as long as the cell, have their long axis in a line with that of 

 the muscular fibres. It is clear, therefore, that we have to do with 

 a cephalic ganglion formed of typical, large, unipolar ganglion cells, 

 which give ofi' two columns of ganglionic substance to the knobs of 

 the proboscis, and also send branches to the suckers. 



Echinodermata. 



Viviparous Chirodota.f — Dr. Hubert Ludwig directs attention to 

 the rediscovery of Oersted's Synaptula vivipara (the Chirodota rotifera 

 of Pourtales). Dr. Ludwig's example was obtained by Professor E. van 

 Beneden from the Brazilian seas. In the body-cavity, an 1 quite free, 

 he found sixteen young, all considerably developed. No indications 

 could be made out of the way by which they would pass to the ex- 

 terior. The specimens were so well preserved that the author has 

 been able to make a complete anatomical investigation, which he 

 promises to publish shortly. The attention of American naturalists 

 to the subject will probably lead to important results. 



Observations on the Temnopleuridae. | — The greater part of 

 Professor Bell's paper on these regular Echinoida is occujjied with an 

 account of the measurements of the more important parts of the tests 

 of these creatures ; the diameter being given in absolute measurements, 

 the percentage values of the measurements of the height, the abactinal 

 area, the anal area, and the actinostome are given in percentages, 

 " Two recommendations," the author says, " present themselves for 

 undertaking this exceedingly laborious task : the changes which occur 

 during growth are at once seen ; and secondly, an aid is given to that 



* 'Zool. Anzeig,' iii. (1880) p. 427. t Ibid., p. 492. 



X 'Proc. Zool. Soc. Lond,,' 1880, p. 422. (1 plate.) 



