GLOSSOLOGY. 



TERMS APPLICABLE TO THE HYDEOID COLONY IN GENERAL. 



Hydrosoma {vSpa, hydra, mythological monster; uw/ta, body). The entire hydroid colony. 



Ectoderm (kro'c, outside; Sep/ua, skin). The more external of the two organized layers of 

 which the body of every hydroid is composed. (Diagrams I and II, e, e, e.) 



Endoderm {IvBov, within ; Sip/na, skin). The more internal of the two organized layers of 

 which the body of every hydroid is composed. (Diagrams I and II, d, d, d.) 



Perisarc {inpl, around; aap^, flesh). The unorganized chitinous excretion by which the soft 

 parts are to a greater or less extent invested. (Diagrams I and 11,/,/,/.) 



Zooids {Iwov, animal; 'tiSoc, form). The more or less independent products of non-sexual 

 reproduction ; the members more or less individualized of which the hydroid colony is composed. 

 (Diagrams I and II, g, (/, k, ¥ , /, m) 



Trophosome (rpo^i), nourishment; aw^ia, body). The entire assemblage of zooids with their 

 common connecting basis, destined for the nutrition of the colony. 



Gonosome (yoroc, offspring; <7(J^a, body). The entire assemblage of zooids destined for the 

 sexual reproduction of the colony. 



Thread-cells. Peculiar bodies consisting of a containing capsule and contained filament 

 destined for urtication, and universally present as a histological element of the ectoderm. (Fig. 

 52, page 118.) 



Palpocils [paljm, I feel; cilium, an eyelash). Microscopic, hair-like, non-vibratile processes 

 of the ectoderm, probably organs of touch. (Pig. 48, page 112.) 



Heteromorphism {inpoq, diverse; /uopffj, form). Diversity of form among the component 

 zooids of the colony. 



Homomorphism {ofwwq, similar; ixQp(^>'u form). Similarity of form among the component 

 zooids of the colony. 



Polymerism (ttoXuc, many ; /ifpoc, part). Simple multiplicity of the component zooids of the 

 colony. 



TERMS APPLICABLE TO THE TROPHOSOME. 



Hydranth (u'Spa, hydra; avQoq, flower). The proper nutritive zooid, or that part of it which 

 carries the mouth and proper digestive cavity. (Diagrams I and II, g, /.) 



Hypostome (utto, under; <TTO(ua, mouth). The distal prolongation of the hydranth, which 

 carries the mouth on its summit. (Diagrams I and II, h.) 



Hydrotheca {v^pa, hydra; e»)/c>/, receptacle). The cup-like chitinous receptacle which 

 protects the hydranth in the calyptoblastic genera. (Diagram II, i, i.) 



Hydrophyton (uSpn, hydra; (^vtuv, plant). The common basis of the trophosome by which 

 its zooids are connected into a single colony. (Diagrams I and II, a, a, a, a, b, h.) 



