THE CRASPEDOTE MEDUSA OLINDIAS AND SOME OF ITS NATURAL ALLIES. 19 



the presence of a closed subumbrellar cavity, a manubrium, and the radial canals at 

 a stage corresponding in other respects to that of the Trachomedusse, in which there 

 is as yet none of these parts, is a point that seriously interferes with the supposition 

 that the young medusae studied by Lankester were derived from the egg-cell (Brooks, 

 '86). Some leptoline medusae proliferate by budding when young, and produce ova 

 when older. 



As to the hydroid described by Parsons, Bourne, and Fowler, it is not known for 

 certain whether it is a member in the life-history of Llmnocodium, although this 

 supposition must be allowed to be very probable. Some light will perhaps be thrown 

 on this point by the French naturalists who have recently observed the medusa in a 

 lily tank in the Zoological Garden of Lyon (Vaney et Conte, : 01), or by the collection 

 from Mr. Moore's expedition to Lake Tanganyica. 



Any one who is acquainted with the Narcomedusae, and especially with their 

 marginal sense-organs, will hardly agree with the proposal of Giinther to place Lim- 

 nocnida, even provisionally, in that group. 



In conclusion I shall add a synopsis of the Olindiadae, which will bring forth their 

 distinctive characters and their natural relationships more clearly, though neces- 

 sarily in a schematic way. 



Subfamily: Olindiadae. Eucopidae with two sets of tentacles, velar and exum- 

 brellar, the former springing close to the base of the velum, and the latter at variable 

 distances from it, but always from the exumbrella and connected with the circular 

 canal by endodermal roots. Marginal vesicles numerous, two on either side of the 

 base of the exumbrellar tentacle. Manubrium well developed and quadrate, with 

 distinct lips. Radial canals four or six. Gonads primarily continuous folds of the 

 walls of the radial canals. With an adhesive disk on each exumbrellar tentacle. 



SYNOPSIS OF THE GENERA. 



1. Velar tentacles just as numerous as the exumbrellar 3. 



2. Velar tentacles more numerous than the exumbrellar 5, 6. 



3. Velar tentacles all rudimentary, in the form of basal bulbs .... Gonionema. 



4. Velar tentacles all filiform Halicalyx. 



5. Radial canals four Olindias. 



6. Radial canals six Olindioides. 



Gonionema (= Gonionemus) A. Agassiz. 



Agassiz, '62, p. 350. Haeckel, '79, p. 146. 



