96 



COMPARATIVE ANATOMY. 



These are — 



1) Locomotive Persons (Nectocalyces) : those conform most 

 completely to the Medusa-type, and are united together by twos 



Fig. 33. Some colonies of Siphonoiahora. ADiplujes campanulata. B A group 

 of appendages of the stem of tlie same Diphyes. C Physophora hydrostatica. 

 A separate nectocalys of it. E Cluster of female generative buds of A<jalma Sarsii. 

 D a Trunk or axis of the colony, d Air-bladder. m Nectocalyx. c Cavity in 

 uectocalyx, invested by a contractile membrane, v Canals in the vralls of this cavity, 

 o Opening of the nectocalyx. t Bracts (in c represented by tentacles), n Stomach. 

 i Fishing-lines, g Generative organs. 



(Diphyida)), or, by a larger number, to form a swimming column 

 (PhysophoridfB)j which occupies the end of the stem (Fig. 33, 

 A G, m B), and which, therefore, takes the lead when the colony is 

 moving, and is directed anteriorly. 



2) Nutritive Persons are present in the second division of 



