38 SUMMARY OF CURRENT RESEARCHES RELATING TO 



domain of echinology, considering the relationship hitherto recognised 

 of Echinoneus to the Atelostomata." The presence of teeth would 

 transfer the genus to the vicinity of such types of the exocyclic 

 Gnathosfomata as Holectypus, Discoidea, Pygaster (Echinoconidae), and 

 more remotely to the Conoclypidae. "The demonstration of this 

 interesting relationship would be interesting in itself, but its great 

 importance lies in the fact of the disappearance of the masticatory 

 apparatus at a very early age. Young specimens of Echinoneus measur- 

 ing 5 - l mm. in length, and but slightly larger than those on which 

 teeth were observed, have no teeth or lantern, and nothing is left of 

 them but the presence of small auricles, so that in the older and adult 

 stages of Echinoneus its relationship to the Spatangoids is in no way 

 modified." 



Luminosity of Ophiuroids.* — Iwan Sokolow has studied this in a 

 number of northern species — Ophiacantha bidentata Retzius, Ophioscolci 

 glacialis Midler and Troschel, Ophiura sarsi Liitken and Ophiopholi* 

 aculeata h. 



The luminescence is not spontaneous, but is induced by mechanical, 

 chemical, thermal and other stimuli. It is intra-cel hilar, no luminous 

 secretion being produced. It is seen on the spines and on the plates of 

 the arms, especially on the lateral plates. As separated arms and even 

 spines may be luminous, it is evident that the central nervous system is 

 not indispensable. The basis of the luminosity seems to be a fluid 

 substance, which, on treatment with fresh water, may diffuse out over 

 the whole arm from specially luminous points. There is no luminosity 

 after death. Microscopic examination reveals the presence of numerous 

 glandular cells with granular contents and also homogeneous fibrous 

 strands, both giving a characteristic brown-violet colouring when treated 

 with thionin. But the meaning of the strands is doubtful. 



Systematic Position of Rhabdomolgus Novas -Zealandise.f — 

 S. Becher discusses this species, which Dendy and Hindle established 

 in 1007, and gives many reasons for separating it off from Rhabdomolgus, 

 and establishing for it a new genus which he calls Kolostoneura, in 

 reference to the great reduction of the radial nerves. 



Coelentera. 



Movements and Sensory Reactions of Veretillum cynomorium.J 

 Georges Bohn describes the behaviour of this colony (Pennatulacea), 

 which passes from complete relaxation to turgidity and from insensi- 

 bility to exquisite sensitiveness. The chemical equilibrium of a cell 

 which has been expanded is destroyed ; the return to equilibrium shows 

 two successive phases, the first of " sensibilisation," the second of 

 " desensibilisation." 



Development of Lucernarids.§ — W. "Wietrzykowski finds that a 

 planula emerges from the egg and lives freely for a day or two. They 



+ Biol. CentralbL, xxix. (1909) pp. 637-48 (6 figs.). 



t Arch. Zool. Exper., i. ser. 5 (1909), Notes et Revue, No. 2, pp. xxxiii.-xliii. 

 (1 fig.). t C.R. Soc. Biol. Paris, lxvii. (1909) pp. 484-7 (1 fig.). 



§ Ccmptes Rendus, cxlix. (1909) pp. 746-9. 



