ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 967 



Eocidaris.* — Dr. K. Kolescli has made a study of the characteristics of 

 Eocidaris keyserlingi. In contrast to the true Cidaridfe it is pointed 

 above ; there are three different kinds of spines ; individual variations were 

 observed. It is not a Palechinid, but a Euechinid, for there are alvi^ays 

 two rows of interambulacral plates ; mathematical computations show that 

 there were twenty rows of plates, all the plates are pentagonal, and the 

 lateral bounding line of the interambulacral areas is zigzag or notched. 



New Holothurians.t — Prof. F. Jeffrey Bell gives descriptions of some 

 new sjjecies of Holothiirians from various localities. Cucumaria sancti- 

 johannis is remarkable for the great reduction of the calcareous ring, the 

 interradial pieces of which are fine filaments, and for the fact that the 

 retractors of the pharynx are two-thirds the length of the whole body, and 

 macroscopically, though not microscopically, seem to be tendinous for the 

 greater part of their length. Cue. inconspicua has the suckers almost, 

 though not quite, regularly restricted to the ambulacral areae, and so affords 

 an argument against the distinction of the species of Cucumaria into two 

 genera, according as the suckers are confined to the ambulacra, or scattered 

 over the body. Holotlmria inermis is remarkable not only from the want 

 of spicules, but also by the absence of the calcareous oesophageal ring; 

 H. ssecularis has none of the turriform spicules which are so generally 

 present in the integument of the species of this genus. 



Colochirus Lacazii.| — M. E. Herouard describes a small Holothurian 

 found near Eoscoff at very low tide, which is interesting as being the first 

 representative of this genus which has been found in European seas. It is 

 white in colour and may reach a length of 70 to 80 centimetres. Its 

 affinities with described forms are not pointed out. 



Coelenterata. 



Regeneration of Polypes.§ — Prof. M. Nussbaum reports that the con- 

 tinuation of his experiments confirms the experiences of Trembley. Arms 

 of polyps cut off without any of the substance of the body attached always 

 perish, but tentacles that retain ever so small a portion of the mouth-ring 

 can form new polyps. This, he says, is owing to the absence in the 

 tentacles of undifferentiated cells, which in the stomach portion replace the 

 loss of the older and necessary tissues, and can be applied to the formation 

 of the reproductive products. 



Structure of Cunoctantha octonaria m adult and larval stages. || — 

 Mr. H. V. Wilson gives an account of this medusa, whose larval existence 

 in the bell-cavity of Turritopsis nutricola has been described by M'Grady 

 and by Brooks. The history of the form does not seem to confirm Prof. 

 Hackel's idea that the difference between the Narcomedusae and Trocho- 

 medusBB has been brought about by the migration of the tentacles from the 

 umbrellar margin dorsalwards, for in Cunoctantha the four primary 

 tentacles do not reach their ultimate position by a migration from the 

 margin of the umbrella. Their final position is due to the outgrowth of 

 intertentacular lobes, and to the growth of the velum, which fills up the 

 interlobular notches, and then bends in to form the horizontal velum. The 



* Jenaische Zeitschr. f. Naturwiss., xx. (1887) pp. 639-65 (1 pi.). 



t Proc. Zool. Soc. Lond., 1887, pp. 531-4 (1 pi.). 



X Comptes Kendus, cv. (1887) pp. 23-1-6. 



§ Verh. Naturh. Ver. Bonn, xliv. (1887) pp. 10-11. 



II Studies Biol. Labuiat. Johna-Hopkius Univ., iv. (1887) pp. 95-107 (3 pis.). 



