ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 59 



In some notes on the development of Irene pellucida, whicli is so 

 common in the Adriatic from October to March, Glaus states that 

 it is possible that the polyp-form of this Medusa is a Campanulina. 

 The first rudiment of the tentacles appears as an outgrowth, present- 

 ing brownish granular concretions, and having a pore at its tip ; 

 these j)ores are looked upon as being the orifices for subjacent glands, 

 which probably have the function of renal organs, and which are 

 formed by the endodermal investment of the adjacent portion of the 

 circular vessel ; by direct observation one may convince oneself that 

 the brown granules and refractive concretions do escape by these 

 pores to the exterior. The genital products appear to become matured 

 in specimens of very various sizes. Some notes on Phialidium 

 variahile complete the paper. 



Fission of Phialidium variabile.* — Dr. M. Davidoff states that 

 he has observed in this Leptomedusa that a second stomogastrium 

 becomes formed at the base of the stomach as a small downwardly 

 projecting bud ; this happens before the tentacles are all developed. 

 The bud gradually grows, and after some time a mouth breaks 

 through. The whole medusa now commences to elongate, and the 

 stomogastria occupy the centres of the ellipse ; two radial canals 

 now open into each stomach and between the two mouths there is 

 an intergastral canal. After these and other changes are effected, 

 the creature is ripe for fission ; the plane of division lies between the 

 two stomogastria, and almost always at right angles to the long axis 

 of the ellipse ; the constrictions deepening, the medusa is divided 

 into two nearly equal halves. In some cases there is a third stomo- 

 gastrium develoijed. The author reminds us that Kolliker, many 

 years ago, noticed a process of fission in StomohracJiium mirahile. 



Crambessa tagi.f — Professor E. Greef points out that this 

 Portuguese Medusa affects the mouths of rivers, and makes its way 

 into landlocked bays. He has found a wide vessel running within the 

 oral fold ; the two pairs of vascular branches which are given off 

 from the short central transverse vessel, open, together with the eight 

 arm-vessels, in the central cavity ; the outgrowths above these central 

 oral vessels have just the same structure as the lobes of the arms, 

 into which they pass directly, and may therefore be regarded as 

 "sucking knobs" or oral frills. Each of the eight arm-vessels 

 divides into four longitudinal vessels, one of which is median ; the 

 three peripheral ones are connected by transverse anastomoses with 

 the axial, and give off branches to the appended lobes. 



The eight sensory organs agree in their external and general 

 internal structure with those of the Hertwigs' second group of 

 Acraspedota ; the terminal network, in which the crystals lie, is 

 regarded by the Hertwigs as being formed from the vessel which 

 runs along the arm; Greef, however, thinks that this plexus is 

 formed from the mesoderm, while the nerve-band breaks up into a 

 fine nucleated plexus, which makes its way into the meshwork which 



* Zool. ADzeig., iv. (1881) pp. 620-2. 

 t Ibid., pp. 568-70. 



