ZOOLOGY AND BOTANY, .MICROSCOPY . ETC. 53 



The luminosity is due to mucus, which is secreted by cells of the 

 external epithelium at the tip of the tube-foot. It accumulates in the 

 intercellular spaces, and passes out by apertures in small papilla? at 

 the tip. The luminosity is extra-cellular. 



The animal produces non-luminous as well as luminous mucus ; 

 both are soluble in hydrochloric acid. Mucus glands occur also in the 

 tube-feet of other Echinoderms, e.g., Astropecten aurantiacus, in the 

 sensory buds of Ophiothrix fragilis, and in the tentacles of Antedon 

 rosacea. The mucus seems to help adhesion in Amphiura squamata and 

 Ophiothrix fragilis, both of which are able to climb up vertical walls. 



Abnormality in Test of Echinolampas.* — R. Fabiani describes in 

 the fossil test of this sea-urchin a peculiar abnormality in the ambulacra! 

 plates, especially in two of the areas of the trivium. The poriferal 

 zones of one series converge rapidly towards those of the other series in 

 the same ambulacrum, they almost unite, and then they suddenly 

 diverge again and follow their usual course. 



Development of Ophiothrix fragilis. f — E. W. MacBride sum- 

 marises the leading points in the development of Ophiothrix fragilis. 

 An important discovery made in the course of his investigations is that 

 there are two types of development, depending on whether fertilisation 

 is effected naturally or artificially. For example, if the former, seg- 

 mentation results in the formation of a thick-walled blastula ; if the 

 latter, a solid mass of cells or morula results. The abnormal develop- 

 ment has a considerable resemblance to the normal development of 

 Ophiura brevis, and is of interest as showing how far-reaching in its 

 influence on the subsequent development is the condition of the egg at 

 the moment of fertilisation, and the idea is suggested that here, perhaps, 

 is to be found the origin of variations. The author remarks that " we 

 must assume that eggs are capable of fertilisation before they are quite 

 ripe, and that the fact that eggs can be fertilised is no proof that they 

 are fully ripe, or that the resulting development is normal. This con- 

 clusion has, I think, a somewhat important bearing on the experimental 

 studies for which the eggs of Echinodermata have furnished the material. 

 Notably the statements which some authors have made about obtaining 

 ripe eggs from sea-urchins like Strongylocentrotus all the year round 

 must be received with great caution." On the disputed question of the 

 homology of the right hydroccele, it is noted that in Ophiothrix fragilis 

 it is from the beginning on the risrht side of the larva. 



- 



New Zealand Holothurians.J — Arthur Dendy and E. Hindle give 

 an account of some Holothurians from Xew Zealand, amongst which 

 they find six new species. Of these Rhabdomolgus novw-zealandicB is 

 the most remarkable; by its discovery the view is confirmed that 

 spicules are really absent in this genus, which has hitherto been dis- 

 credited by systematists, and which must now be revived. 



* Atti Accad. Sci. Veneto-Trentino-Istriana, iv. (1907) pp. 75-8 (2 figs.). 

 t Proc. Roy. Soc, Series B, lxxix. (1907) pp. 440-5 (4 figs.). 

 j Journ. Linn. Soc, xxx. (1907) pp. 95-125 (4 pis.). 



