372 W. K. BROOKS ON THE LIFE-HISTORY 



single larva ami this becomes converted into a single adult. There is no asexual multi- 

 plication, no parasitism and no alternation of generations. 



2. In Can/ma oclonaria, the hydra embryo, while still ciliated like a planula, but 

 furnished with a mouth and two tentacles gains access to the bell of a Hydromedusa, 

 Tnrritopsis, where it lives as a parasite, and produces other larvae, like itself, by bud- 

 ding. The first larva, like all the others, becomes a medusa, so that we have budding 

 and parasitism, but no alternation. 



3. The Cunina larva, which inhabits Geryonids, is essentially similar, but the first 

 larva or egg-embryo does not become a medusa, so that we have alternation as well as 

 budding and parasitism. 



4. As no one has proved that the Cunina larvae found in Cuninas do not pass in from 

 outside, and as their history is like that of the species above noticed, there is every rea- 

 son for believing that they also arc parasites. 



Section II. The Trachomedusae. 



Plates 41,42. 



Liriope is a representative of the third of the four orders into which Ilaeckel divides 

 the Hydromedusse; the Trachomedusae,, or veiled medusae, with auditory tentacles, which 

 are either free on the bell margin or inclosed in auditory vesicles, with endodermal otolith- 

 cells. Ocelli on tentacular bases usually absent. Reproductive organs on the course of 

 the radial canals, which are four, six or eight in number, often with blind centripetal ca- 

 nals between them. Veil, thin and wide. Ontogeny, as far as it is known, hypogenesia 

 or direct development without alternation, but usually with metamorphosis. 



It is a representative of his fourth family or the Crenjonidce : Trachomedusae with four 

 or six radial canals, with broad, leaf-like reproductive organs; along proboscis, eight or 

 twelve peronia, and closed auditory vesicles, which lie on the axial sides of the peroniain 

 the gelatinous substance of the umbrella-margin; and to the first subfamily, the 

 Liriopidae, or Geryonidae with four radial canals, four reproductive organs and eight 

 auditory vesicles. He divides the subfamily into two genera: Lirantha with eight 

 permanent tentacles in the adult; and Liriope, with only four; and he places our species 

 in the first genus. 



Haeckel has undertaken the very perplexing and laborious task of introducing order 

 and system into the confused mass of fragmentary observations which have been printed 

 regarding the Geryonidae, and as his writings upon the subject introduce order where 

 all had been confusion, and as he himself is more familiar than any other naturalist with 

 the species and genera of the family, I hesitate to depart in any particular from his sys- 

 tem: but inasmuch as specimens of our Liriope scutigera are sometimes found with 

 four, five, six or seven tentacles, as well as specimens with the unusual number eight, 

 I cannot believe that his two genera Liriantha and Liriope are natural, and I therefore 

 retain the generic name Liriope for our species. Fewkes' statement (Acalephs from the 

 Tortugas, Bull. Mus. Comp. Zool., ix, No. 1, p. 279) that Ilaeckel bases his two genera 



