178 ME. E. T, BROWNE — BISCATAN PLANKTON: 



of the umbrella are slightly rounded, but their shape is not very well seen owing to the 

 curling inwards of the margin. Some of the sense-organs are broken off, but many 

 remain. Their number, however, is ascertainable by the narrow rows (the otoporpse) of 

 uematocysts Avhich extend a little way up the ex-umbrella side of the marginal lobe. 

 Each otojjorpa is in continuity with a minute bulb containing nematocysts on the 

 margin of the umbrella, and upon every bulb a sense-organ is sitviated. 



Development of the Jledusa-buds. — The medusa-buds form a nearly complete series 

 Avhich shows very well the course of their development. They resemble in external 

 appearance the figures given by Maas (1892) and by Chun (1894) for the development 

 of a Ctmina-hvid. 



Two adjacent pouches of the stomach were removed and cut into sections. The 

 sections show that a bud begins as a hollow outgrowth of the wall of the pouch (fig. 2, 

 -B', J3"). Sections were also cut of a later stage ; its shape and structure agree with the 

 figures given by Maas (1892, fig. 23) and by Chun (1894, fig. 64, v.). It is evident from 

 these sections that the buds are developing directly from the wall of the pouch and that 

 tliey are not of a parasitic origin. 



The largest and most advanced medusa-bud shows the outgrowth of the eight 

 tentacles, the velum, the eight marginal lobes, and two sense-organs upon each lobe. 

 This medusa-bud was removed from the poucli for examination, and an opening 

 (iig. 1, 0.) into tlie cavity of the pouch was found. 



So far as 1 know, no species of Cimoctantlia or Cunina have hitherto been described with 

 medusa-buds developing directly from the wall of the stomach or its pouches. Brooks 

 (188G), in his account of tlie life-liistory of the Narcomedusa?, says : " No one has shown, 

 by careful examination, that any adult Cunina produces buds from its stomach or from 

 any other part of its body, and there is every reason for believing that the Cunina larvye 

 found in their stomachs are parasites, like those found in Tiwritopsis and in Geryonids, 

 and that the Cunina larva found in the stomach of an adult Cunina does not necessarily 

 belong to the same species with the adult." 



A medusa bearing medusa-buds is usually at an early or intermediate stage of 

 development, and does not show all the chai-acters found in the fvilly grown adult with 

 gonads. Canoctantha fowleri has yet to be connected with an adult medusa bearing 

 gonads. At its present stage it has eight tentacles, which admits it to the genus 

 Cunoctantlia ; but in the adult stage it may have more than eight tentacles, in which 

 case it would belong to the genus Cunina. 



^3 



Pegantha sp. 



There are two specimens which are not in good condition. They look like young 

 stages of a Teyantha, and are without gonads. 



(a) Umbrella about 7 mm. in width and 5 mm. in height ; 13 tentacles alternating 



with 13 marginal lobes. About three sense-organs on each lobe. 

 (6) Eleven tentacles and eleven lobes. About five sense-organs on each lobe. 

 Occurrences: 200 to fathoms. ZQ g (1). 

 350 to fathoms. 36 I (1). 



