SCYPHOMEDUS.F. OF THE AUSTRALIAN SEAS. 7 



of the sub-umbrella, which at certain seasons appear filled with the larvae. 

 There are numerous other amusing arrangements in the different species, whilst 

 in some, as for instance in our Crambessa mosaica, no larvse have been observed 

 in the body of the female medusa?. 



At the time when the larva attaches itself the tentacles make their appear- 

 ance. One is formed first, and becomes clearly visible before the second 

 opposite one commences to grow. A pair of tentacles then grows out between 

 the two primary ones, so that a polyp, with four tentacles and a mouth in the 

 centre of them, results. Four longitudinal thickenings are then produced in 

 the wall of the gastral cavity, which divide the latter into four separate 

 chambers, analogous to the chambers in the gastral cavity of the Anthozoa. 

 The number of tentacles increases in an irregular manner to sixteen. In most 

 cases this is the limit of the number of tentacles. The Scyphystoinpe of 

 Crambessa mosaica, recently seen by me, possess thirty-two tentacles. This 

 polyp, which is termed Scyphystoma, grows to a comparatively large size. It 

 may reach, without changing its shape, a length of fifteen mm. These polyps 

 multiply by budding to five or ten, which remain in connection by a tube, 

 shaped stolon in such a manner that the gastral cavities are in free 

 communication with each other. In some species the Scyphystoma does not 

 multiply by budding, but remains solitary. 



The whole of the ectoderm is charged with cfridoblasts. The tentacles are 

 solid, and filled with a peculiar kind of entoderm, consisting of large cells, with 

 thick walls. The mesoderm is developed only in the shape of a supporting 

 lamella, and very thin. Only in the four longitudinal gastral ridges it is more 

 massive. The entoderm consists throughout of uniform granular cells. 

 Muscular fibres are found in the cctodermal lubepithel ; these belong to 

 ectodermal " ISTeuromuscle cells." 



When the Scyphystoma has attained its full size it commences to produce 

 small medusas by a pi-ocess of strabilation. The distal portion of the 

 Scyphystoma is divided into annular zones by transverse circular grooves, 

 which make their appearance at first as insignificant depressed lines, which, 

 however, soon increase in depth, while at the same time the inflated annular 

 zones between them grow rapidly. Their growth commences at the upper 

 distal end, so that we find the distal sections of the strabila much further 

 developed than the proximal ones, and all in proportion to their distance from 

 the base of attachment of the strabila. 



The Scyphystoma, which by this process has been converted into a 

 " Strabila," does not grow in size any more. The grooves become deeper, 

 whilst the margin divides into a number of lobes. These are mostly eight in 

 number. In Phyllorhyza I have observed sixteen. These lobes are again 



