84 
CHARLES L. BOULENGER. 
J. E. Moore’s expedition to Lake Tanganyika added much 
to our knowledge of the life-history of Limnocnida, and 
his book, f The Tanganyika Problem/ contains a short account 
of the anatomy (2). 
More recently the study of the excellently preserved 
specimens collected by the late J. S. Budgett in the Niger 
Delta, and by W. A. Cunuington in Lake Tanganyika, has led 
to a more complete understanding of the structure and 
arrangement of the tentacles on the umbrella edge. These 
two collections were described respectively by E. T. Browne 
(3) and B. T. Gunther (4), the latter’s report containing, in 
addition, a short account of some specimens from the Victoria 
Nyanza. 
Whilst recently investigating the movements of the sting- 
ing-cells in the tissues of certain Hydromedusse (5) my 
attention was drawn to some of Gunther’s figures of the 
“ nettle-ring” of Limnocnida, and it occurred to me that a 
detailed investigation of the structure of this characteristic 
organ might lead to an elucidation of the function of these 
thickened bands of ectoderm containing nematocysts, which 
occur with such regularity in the Trachomedusae and Narco- 
medusae. 
Through the kindness of Dr. S. F. Harmer, F.R.S., and 
Mr. R. Kirkpatrick, I obtained permission to study the speci- 
mens of Limnocnida tanganicae in the British Museum 
collection, and was allowed to cut sections of one. The 
specimen selected was one from the large collection made by 
Dr. W. A. Cunnington during the Third Tanganyika Expedi- 
tion of 1904-5, and was still in an excellent state of preser- 
vation, having been carefully fixed in weak osmic acid. 
Sections were prepared by the ordinary paraffin method, 
and were stained with Grenadier’s haematoxylin. 
I purposely selected an individual bearing medusa-buds on 
the manubrium ; Goette’s recent paper on the development 
of the gonophores of the Hydromedusae ( 6 ) has so completely 
revolutionised our knowledge of this subject that I felt that 
it was desirable to reinvestigate the process of bud-formation 
