9^ 



MANUAL OF ZOOLOGY. 



only the new polypites, but the new nectocalyces and repro- 

 ductive organs, and even the branches of the tentacles, are 

 developed on the proximal side of the old 

 ones ; so that the distal appendages are the 

 oldest." — (Huxley.) The process of de- 

 velopment is therefore the reverse of what 

 obtains amongst the Hydroida. 



Diphyes (fig. 19), which may be taken 

 as the type of the Calycophoridcs, consists 

 of a delicate filiform ccenosarc, provided 

 proximally with two large mitre-shaped nec- 

 tocalyces (», if), of which one lies entirely 

 on the distal side of the other. The pointed 

 apex of the distal nectocalyx is received into 

 a special cavity in the proximal nectocalyx. 

 The " hydroecium " {K) is formed partially 

 by this chamber in the nectocalyx, and par- 

 tially by an arched groove prolonged upon 

 the inner surface of the distal nectocalyx, 

 within which the coenosarc moves freely up 

 and down, and can be entirely retracted tf 

 necessary. The upper part of the ccenosarc 

 dilates into a small ciliated cavity, from 

 which are given off two tubes, which pro- 

 ceed respectively to the distal and proximal 

 nectocalyces, where they open into the cen- 

 tral chamber from which the nectocalycine 

 canals take their rise. The upper portion 

 of this small ciliated cavity is prolonged 

 calyx; /i Hydroecium; proximally into the larger chamber of the 



c Coenosarc, carrying ^ ^ ' ^t, n-\, / \ u 



poiypites each with Its somatocyst. 1 he coenosarc (^) bears 

 bract and tentacle. polypites, each of which is protected by a 

 delicate glassy " hydrophyllium." 



Fig. 19. — Calycophori- 

 dae. Diphyes apfietidi~ 

 culaia (after Kalliker). 

 V Proximal nectoca- 

 lyx : tfi Distal nectO' 



Divisions of the Calycophorid^.— (After Huxley.) 



Fam. I. Diphydee. — Nectocalyces not more than two in number, and of 

 a polygonal shape. Hydroecium of the proximal nectocalyx complete, or 

 closed posteriorly. Hydrophyllia well developed. 



Fam. II. Sphczronectidce. — Nectocalyces probably not more than two in 

 number ; the proximal nectocalyx spheroidal, with a complete hydroecium. 

 No hydrophyllia (?). 



Fam. HI. PrayidcE. — Nectocalyces two in number; hydroecia incom- 

 plete and groove-like. Polypites protected by hydrophyllia. 



Fam. IV. Hippopodida. — Nectocalyces numerous ; hydroecia incomplete. 

 Polypites not protected by hydrophyllia. 



Order II. Phvsophorid.^. — This second order of the 



