Introduction to Animal Morphology. 95 



sessile unilateral hydrotheca, scattered degraded hydranths, 

 consisting of cup-like cavities of the perisarc filled with pro- 

 toplasm, in which nettle-cells are embedded, forming nettle- 

 batteries or nematophores, for the protection of the colony ; 

 gonozooids fixed,* simple, axillary, ex. Plumularia. 



Order 4. Monopsea (Alhritui] Possibly only a pro- 

 visional order, including those forms with no known 

 trophosome separate from blastochemes, and in which 

 the medusae develop directly from the egg. 



Four families are included : 



i. Geryonidae manubrium elongated ; lithocysts inter- 

 tentacular ; sex-organs in flat masses along the radial canals, 

 which may be four (LiriopinDe) or six (Geryoninae) ; in the 

 former there are no centripetal canals, often a tongue-like 

 process, and eight (Xanthea) or four tentacles (Liriope) ; or 

 no tongue-like process, and eight (Glossoconus) or four ten- 

 tacles (Glossocodon). In the latter there are many blind 

 centripetal canals, with (Carmarina, Fig. 12, E), or without a 

 central tongue-like process (Geryonia), except in Leuckartia, 

 where these canals are absent. 2. ^Eginidae disc with 

 tentacles springing above the margin ; radial canals, pouch- 

 like, wide 4-32; lithocysts marginal; Cunina has simple 

 tentacles, each with a conical cartilage at the base, springing 1 

 opposite the stomach pouches (in /Egina they alternate), and 

 a broad simple mouth. /K.^innpsis, which has oral tentacles, 

 en traced from its ei^ with no trophosome stage. 

 Agassiz m, ; :>arate family Uramltuhu for allied, but im- 



ly known forms. 3. Trachynemiche blustochemes 

 with no lon^ manubrium, and still" tentacles ; disc bell-shaped 

 irllat Rliopaloneina\ 4. ( h ton huke with 



1 quadrangular manubrium, having a radial canal at 



::ilal masses, lour iii tin- mamibrium ami 

 four in the sub-unibn-!! iiis. 



'J i: :n of the i). to pn>ttu<i< 



naif). 'I i Mnt to he used in 



Miiul.i h.is no 



nettle- 



