REPORT ON THE SIPHONOPHOR^E. 313 



the same in all members of this order. The stem of the gonostyle is always richly 

 ramified, and bears on each branch one or several sexual palpons (gq), a single gynophore 

 or female medusome (f), and a great number of androphores or male medusomes (h). 

 These latter become mature whilst attached to the gonodendra ; they have ovate or 

 club-shaped spermaria, with a more or less rudimentary umbrella (PI. XXIII. fig. 8, h ; 

 PL XXV. fig. 7, h; PL XXVI. fig. 8,h). 



The larger female gonophores, however, are probably always detached in the im- 

 mature state from the stem, and become mature as free Anthomedusae. Their 

 umbrella (f in the figures quoted) is well developed, campanulate or pyriform, with four 

 radial canals and a ring-canal, and a broad velum around the ostium. The manubrium, 

 in the wall of which the eggs ripen, seems to be developed usually after the detachment. 

 It is not visible in the sessile gynophore, or forms only a small tubercle in the centre of 

 the subumbrella (PL XXIII. fig. 8,fm). The apex of the gynophore is attached to the 

 branch of the stem by a large conical pedicle (PL XXIII. fig. 8, f). These pedicles 

 remain attached to the stem of the gonodendron, when the ripe gynophores are detached. 

 Some very large specimens of Caravella maxima, which I observed in the Bay of Alge- 

 siras (Straits of Gibraltar), in March 1867, bore voluminous gonodendra, the androphores 

 of which were filled with ripe sperm. Some of their numerous branches possessed each 

 a single medusiform gynophore (PL XXVI. fig. 8, f ), whilst in other branches only its 

 conical pedicle was visible, the campanulate umbrella having been detached (compare 

 Chun, 86, p. 1168). 



The Cystalidae, Epibulidaa, and Rhizophysidse seem to possess on each branch of the 

 gonostyle a single sexual palpon only, corresponding to the single gynophore (PL XXIII. 

 fig. 8) ; whilst the Salacidse and Physalidae bear several gonopalpons on each branch. 

 The gonopalpons of the Physalidse are covered inside by the same black hepatic villi as the 

 siphons, and thus prove to be modified mouthless siphons (PL XXVI. fig. 8, q). The 

 sexual tasters of the Rhizophysidse are often covered outside with peculiar cnidonodes 

 (PL XXIII. fig. 8, gq). 



Ontogeny. — The development of the Cystonectse from the fertilised egg is up to 

 this time cpaite unknown. The ripe eggs themselves have never been observed. The 

 medusiform gynophores are detached early from the trunk, and the special forms of 

 Anthomedusae, in which they produce ova, are not yet known. Very little is known 

 also of the monogastric larvae of the Cystonectse (Cystonula), and of their peculiar 

 metamorphosis. Those of Physalia were first described by Huxley (9, p. 102, pi. x. 

 figs. 1,2) and afterwards by Chun (83, p. 558). The Cystonula of the other families is 

 hitherto unknown. Some light, however, may be thrown upon this complete darkness by a 

 number of larval forms which I captured by means of the tow-net in December 1881, in 

 Ceylon, and which are figured in PL XXII. figs. 1-4. Compare their description below, 

 under that of the family Cystalidse (p. 315). 



(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) Hhllh 40 



