394 SUMMARY OF CURRENT RESEARCHES EJ:LATING TO 



off Villefranclie, and measured in all 24 cm. The nervous system has 

 a close resemblance to that of Halistemma ruhrum, as described by 

 Korotneff. The most characteristic organs are the bracts, of which there 

 is a considerable number; their peculiar appearance is due to the 

 presence, on their surface, of a large number of small, deep-carmine-red 

 dots, which are small glands which open and expel an intensely yellowish- 

 red colouring matter when the animal is captured. These glands are 

 formed of an aggregate of cells, the protoplasm of which is coarsely 

 granulated. About half of the gland is above the surface of the bract. 

 When the colouring matter has been discharged all trace of the glandular 

 cell disappears, and there is only a small excavation surrounded by a light 

 yellow cloud. The tentacles of this new species have a characteristic 

 appearance which is due to the presence of a terminal orifice and to 

 the site of the point of attachment of the accessory filament. All the 

 characters of this new form are fully discussed. 



'Challenger' Siphonophora.* — Prof. E. Haeckel has published a 

 report on the Siphonophora collected by the ' Challenger,' with which 

 he has incorporated notes on other specimens. The generalizations are 

 of interest, but they were made known to our readers at the time of their 

 original publication in Germany.^ Two hundred and forty species are 

 enumerated. The plates, as usual in Prof. Haeckel's works, are of great 

 beauty. 



Monobrachium parasiticuni.| — Herr J. Wagner has some notes on 

 interesting structural characters in this Hydrozoon. The periphery of 

 the colony is characterized by special structures which the author pro- 

 poses to call pseudonematophores ; they probably represent specialized 

 individuals, and form an intermediate stage between true nutrient polyps 

 and nematophores. The subepithelial layer is wanting in most parts of 

 the organism, and the author was unable to find differentiated ganglionic 

 cells. In the hydrorhiza there are often poorly developed nemato- 

 cysts with very short threads and vesicular contents. The urticating 

 capsules have no cnidocils; where this is the case the filament is 

 generally looped, but in Monohrachium it is spirally coiled. The axial 

 tissue of the single tentacle consists of a number of large cells which are 

 irregularly arranged ; it is not separated from the endoderm by the 

 supporting lamella, and the gradual passage of the nutrient into the axial 

 cells may be clearly seen. The gonophore is in the form of an almost 

 completely developed Medusa ; its blind gastric cavity has the form of a 

 spadix and contains a small cavity; in some the circular vessel is 

 distinctly developed, but in others it could not be detected. The nerve- 

 ring is formed of filaments of the subepithelial cells. The endoderm of 

 the tentacle of the medusa-form is made up of ordinary cartilaginous 

 cells, and there is no cavity in them. 



Unripe ovarian cells and similar amoeboid male cells, which only 

 differed in having nuclei which colour more intensely, were often found 

 in the ventral endoderm of the radial vessels. In two cases some 

 maturer cells were found in the genital sacs in their passage from the 

 endoderm of the radial vessels. Smaller cells, which appeared to be 

 younger eggs, were found in the endoderm of the hydrorhiza at the 



* Reports of the Voyage of H.M.S. ' Challenger,' Zoology, vol. xxviii., part Ixxvii. 

 (1888) 380 pp., 50 pis. 



t See thi« Jourual, 1S8S, p. 711. J Zool. Auzeig., xii. (1889) pp. 116-8, 



