314 



THE VOYAGE OF H.M.S. CHALLENGER. 



Synopsis of the Families of Cystonectse. 



I. Suborder Cystonectse monogastrice (Monostelinle). 



Corm with, a single large siphon, representing one cormidium only. A single tentacle 

 on the base of the siphon. A corona of palpons around the base of the large pneu- 



matophore. Pneumatosac without hypocystic villi, 



A. Maceostelinls. 



II. Suborder 



CTSTONECTiE 



POLYGASTR1C.E. 



Corni composed of numer- 

 ous cormidia, each with 

 one or more siphons and 

 tentacles. Cormidia some- 

 times ordinate, at other 

 times irregular. (Primary 

 larva monogastric, Cysto- 

 nula.) 



Trunk of the siphosome , 

 very long and thin, ' 

 tubular, with prolonged 

 internodes. 



B. Brachystelini^:. 



Trunk of the siphosome , 

 short and wide, vesicular ' 

 or bag-shaped, with short- 

 ened internodes. 



Cormidia monogastric, each 

 with a single siphon and 

 tentacle. (Pneumatosac 

 with hypocystic villi), 



Cormidia polygastric, each 

 with several siphons and 

 tentacles. (Pneumatosac 

 with hypocystic villi), 



Cormidia in a spiral corona 

 around the vesicular trunk, 

 beyond the base of the 

 subvertical pneumatophore 

 (with hypocystic villi), 



Cormidia in a multiple series 

 along the ventral side of 

 the trunk, the dorsal side 

 of which is occupied by the 

 subhorizontal pneumato- 

 phore (without hypocystic 

 villi), . 



20. Cystalid*. 



21. Ehizophysida. 



22. Salacidw. 



23. Epibulidae. 



21. Physalidaa. 



Family XX. Cystalid^e, Haeckel, 1888. 

 Cystalidx, Hkl., System der Siphonophoren, p. 44. 



Definition. — Cystonectse monogastricse, with a single large siphon and a single 

 tentacle on the base of the large apical pneumatophore. Base of the siphon surrounded by 

 a corona of palpons. Pneumatosac simple, without radial septa and hypocystic villi. 



The family Cystalidse comprises a single new genus of small, but very remarkable 

 Cystonectse, which differs from all other genera of this order in the monogastric structure 

 of its corm. This interesting genus, Cystalia (PI. XXII. fig. 5), exhibits therefore a 

 relation to all the other polygastric Cystonectse similar to that which the monogastric 

 Circalia or Athoria (PL XXI.) bears to the polygastric Physonectse. 



During my residence in Ceylon I captured by the tow-net several times the elegant 

 form, which I called in my System (95, p. 44) Cystalia larvalis. A very similar, and 

 perhaps identical, form was found in a bottle of the Challenger collection, from Station 

 288 (centre of the Southern Pacific); I named it there Cystalia challengeri. A closer 

 comparison of them makes it very probable that these two species are identical ; the 

 more significant name Cystalia monogastrica may, therefore, be retained for both. 



At the first glance I had supposed that Cystalia larvalis might be only a young form 



