DISCOVERY REPORTS 

 90 



tiny knob with no indication of a medusoid structure; it acts as a stolo-prolifer from which other 

 individuals arise by budding, and all these individuals are successively developed into medusae. This 

 is especially clearly seen in young clusters consisting of only few individuals. In their youngest stage 

 the medusoid buds are knob-like, but very soon they develop a long, hollow proboscis, like a trunk, 

 with a terminal mouth-opening. The proboscis usually attains a considerable length, before the 

 umbrella of the future medusa makes its first appearance as an annular dilatation of the proximal part 



of the bud. 



I have observed this in all the present specimens. Further development proceeds in rather different 

 ways in the different species, and at the time of liberation the young medusae, derived from the four 

 different hosts, differ so much from each other that they undoubtedly must belong to four different 

 species of narcomedusae. Presumably the infection takes place in a way similar to that described by 

 Brooks (1886), where an actinula-like larva attaches itself to the subumbrella of the host (a Turritopsis) 

 by means of its capitate tentacles and gives rise to a number of medusa buds; but in the specimens 

 observed by him the primary larva itself was transformed into a medusa with a long proboscis and an 

 umbrella, and all the medusa buds were, like the primary individual, liberated at a stage provided with 

 two kinds of tentacles. These consisted of four large capitate tentacles directed upwards and four 

 secondary, still very tiny tentacles, whereas, on the contrary, in all the specimens observed by me all 

 the tentacles of the medusa buds are of equal size and structure, and the primary individual remains 

 in a polypoid stage. Accordingly the development must be regarded as a true metagenesis. 



Attached to Bougainvillia platygaster 



(PI. VII, figs. 3, 4) 



St. 680. 30. iv. 31. 22° 36' S, 30' 01' 30" W. Net: TYFB 260-0 m. 

 St. 683. 2. V. 31. 16° 48' S, 29° 54' 45" W. Net: TYFB 290-0 m. 



These localities are off the east coast of Brazil. 



The specimens of infected Bougainvillia are all of about the same size, 9 mm. in diameter, and all 

 of them are well preserved; all their organs are retained and undamaged (in contradistinction to the 

 other species, see below), but gonads are not developed. The clusters of narcomedusa larvae are always 

 attached to the subumbrella of the host inside the triangular pouches between the subumbrella 

 and the aboral wall of the square, flattened stomach. As long as the clusters are very young, with 

 only few buds, the medusoid buds are usually also seen inside the periphery of the stomach, but in 

 further stages of development the cluster hangs outside the stomach wall, the buds bending their 

 proboscis towards the mouth of the host. The capitate tentacles of the primary individual maintain their 

 grip above the aboral wall of the stomach (PI. VII, fig. 3); they vary in number between four and six. 



St. 680, two specimens infected, (i) With four very small clusters, one in each interradius. Two 

 of them have only one or two tiny buds still without a proboscis, in the third cluster one of the buds 

 has a short proboscis ; in the fourth cluster two buds are provided with a long proboscis and one of 

 them with a small umbrella, scalloped in the margin and with tiny rudiments of 8 tentacles. (2) With 

 five clusters of very numerous medusa buds in different stages of development, two clusters in one 

 of the interradial quadrants, one in each of the others (PI. VII, fig. 3). The 8 tentacles first appear as 

 tiny knobs, but gradually they become elongated and pointed; in young stages they point upwards, 

 but later on they are directed downwards; long and deep peronia are soon developed. 



St. 683, one specimen infected. With four clusters of larvae, interradially situated, two of them con- 

 sisting of only two buds, both with a long proboscis; a third cluster has three buds, one of them with 

 a small umbrella and tiny rudiments of tentacles; in the fourth cluster four of the buds have a long 



