712 SUMMARY OF CURRENT RESEARCHES RELATING TO 



mcilusii-livivft Disconiihi ; it lias a marginal circlet of tentacles throughout 

 life, ami ]iroclacc8 the persons of the colony by budding from the 

 Bubumbnlla. 



(4) The Siphonanth.TD, which include the Calycoplioridic, Physo- 

 phorida?, Pueumatopliorida), and Anroi)h()rid!e, have as a primary laiva a 

 bilateral medusa, which is distinguished by a ventral umbrella- cleft, and 

 the possession of a single tentacle (Siphonula). Tlic jjcrsons of the 

 colony are produced by unilateral budding from the gastric wall of the 

 manubrium. 



(5) The primary larva of the Disconanthaj is to be regarded as the 

 ontogenetic re2)et tion of a common and archaic octoradial stem-form 

 (^Archimcda), and its phylogenetic origin is probably t> ba sought for 

 among the Trachomedusfc (^Trachi/nemidse, Pecfi/llidse). 



(6) The piimary larva of the Siphonautlue is to be regarded as 

 the ontogenetic repetition of a common archaic bilateral stem-form 

 (^Protomeda), whose origin is j^robably to be sought for among the 

 Anthomedusffi (Codonidse, Euphyridse). 



(7 ) All the parts which arise by budding from the primary larva of 

 the Siphonophora are either medusiform persons or special organs 

 thereof. 



(8) All the organs which primitively belong to a medusa-person may 

 be comprehended under the medusoma, and that whether they arise from 

 a common basis on the trunk, or se2)arately in various places, in con- 

 sequence of cenogenetic migration or dislocation. The multii^lication 

 of separate equivalent parts (such as nectojihores or bracts) are not to 

 be regarded as multiplication of persons or medusome, but merely of 

 organs. 



(9) Although the medusome arises under two distinct forms these 

 cannot be sharply sejiarated from one another ; in the palingcnetic 

 medusomes the chief organs remain more or less in their primitive con- 

 necticm (as, for example, in the gonophore of Eudoxia) ; in the cenogenetic 

 medusomes the primary organs are more or less dislocated, as in the 

 sterile medusa of Eudoxia. 



(10) The lateral budding of the secondary medusomes (appendages) 

 on the trunk may be solitary or in grouj^s ; the name of cormidia is given 

 to the groups which are composed of several medusomes. 



(11) The cormidia are primitively simple segmental repetitions 

 of a medusome-group in metameric succession, which are separated by 

 free internodes (cormidia ordinata) as in the Eudoxiae of the Calyco- 

 phorida, &c. 



(12) By the breaking up of such primitive cormidia there arose those 

 centralized cormi in which tbe persons bud at various points of the trunk ; 

 in this way the several organs become separated from one another 

 (cormidia dissoluta), eg. Agnlmopsis, Poli/phycs. 



(13) The retrograde development of the several medusomes and their 

 dislocated organs is of very great significance in the development of the 

 Siphonoi)horous colonics, and is greater proportionately to the centraliza- 

 tion of the cormus. 



The several points here noted are then treated separately and in 

 more detail. Notes then follow on monogastric and j^olygastric cor- 

 midia, on the stem or trunk, the nectosoma (or swimming body), and 

 the sii^hosoma (or nutrient body), the nectophores or swimming bells, 

 the pueumatophore or swim-bladder, and the aurophore or air bell ; 



