360 REPORT—1863. 
Il. MorpHonoey or THE GONOPHORE. 
A. Parts of an adelocodonice gonophore. 
An adelocodonic gonophore, when fully developed, consists of the following 
parts (see fig. 5 A, and fig. 6 A, B, C) :— 
1. An external ‘membranous closed sac, ectotheca*. 
2. A second sac lying immediately within the ectotheca, mesothecat. 
3. A system of canals which permeate the walls of the mesotheca, gastro- 
vascular canals. 
4. A third sac, internal to the mesotheca, endothecat. 
5. The generative elements (ova or spermatozoa), contained immediately 
within the endotheca. 
6. A hollow process which occupies the axis of the gonophore, whose 
cavity is in communication with the somatic cavity of the trophosome, and 
round which the generative elements are produced, spadiv§. 
It is not usual, however, for the adelocodonic gonophore to possess all the 
parts here enumerated, the mesotheca and gastrovascular canals in particular 
being often entirely suppressed. The only absolutely constant parts are 
spadix, endotheca, and generative elements. 
B. Parts of a phanerocodonic gonophore. 
In a completely developed phanerocodonic gonophore the following parts 
may be distinguished (see fig. 5 B and fig. 6 D):— 
a. An external membranous closed sae, ectotheca. 
b. Within the ectotheca a peculiar body known as a gymnophthalmic me- 
dusa. 
The gymnophthalmie medusa, which thus constitutes the essence of the 
phanerocodonie gonophore, consists of the following parts :— 
1. An open contractile bell or disc, umbrella. 
2. A central hollow body hanging from the summit of the umbrella-cavity, 
and bearing a mouth at its free extremity, manubrium ||. 
3. A system of canals excavated in the substance of the umbrella, and 
lined with endoderm. They consist of a set of radiating canals and of a cir- 
cular canal: the former are in by far the majority of cases four in number, 
or some multiple of four; they open by their proximal extremities into the 
base of the manubrium, and thence extend at exactly equal intervals towards 
the margin of the umbrella, while the circular canal runs round the umbrella 
immediately within its margin, and receives the distal extremities of the ra- 
diating canals which here open freely into it. These two sets, radiating and 
circular, constitute the gastrovascular canals. 
4. Contractile tentacula which spring from the margin of the umbrella. 
5. Either accumulations of pigment-granules, named ocelli, which occur at 
the base of the tentacles, and in which a refractile body is occasionally im- 
bedded, or else peculiar capsules, lithocysts, which are attached to the margin 
of the umbrella, and enclose one or more transparent refractile corpuscles. 
6. A membranous extension (velum) of the margin of the umbrella over 
* 'Exros, outer, and @7)«n, a sheath. 
t Meoos, middle, and @yKn. 
*Evooy, within, and 07K. 
; Brak, the closely crowded spike forming the inflorescence of a palm-tree, Ke. 
|| Manubrium (Latin), a handle. It is the “pedunele,” “ proboscis,” “ stomach,” &e., of 
authors. The term manubrium was suggested by me some years ago (Proc. Roy. Soc. 
Edin. 1858), in order to obviate the incorrect or equivocal significance which attaches itself 
to the names usually employed for this part. 
