GLOSSARY. 335 



HIS-TOI/O-GY (Gr. hiatos, a web ; logos, a discourse). The study of the tissues ; 



more especially of the minuter elements of the body. 

 HOL-O-CEPH'A-LI (Gr. holes, whole ; kephale, head). A sub-order of the 



Elasmobranchii, comprising the Chimcerce. 

 HOL-O-MET-A-BOL'IC (Gr. holos, whole; metabole, change). Applied to insects 



which undergo a complete metamorphosis. 

 HOL-O-STO'MA-TA (Gr. holos. whole ; stoma, mouth). A division of Gasteropo- 



dous Molluscs, in which the aperture of the shell is rounded, or "entire." 

 HOL-O-THU-ROI'DE-A (Gr. holos; thura, door ; and eidos, form). An order of 



Echinodermata comprising the Trepangs. 

 HOM-O-CEK'CAL (Gr. homos, same ; kerkos, tail). Applied to the tail of Fishes 



when it is symmetrical, or composed of two equal lobes. 

 HO-MO - GE'NE-OUS. 

 HO-MO-GAN'GLI-ATE (Gr. homos, same ; gagglion, a knot). Having a nervoua 



system in which the ganglia are symmetrically arranged (as in the Annu- 



losa, for example). 

 HO-MOL'O-GOUS (Gr. homos ; and logos, a discourse). Applied to parts which 



are constructed upon the same fundamental plan. 

 HO-MO-MOR'PHOUS (Gr. homos; and morphe, form). Having a similar external 



appearance or form. 



HU'ME-BUS. The bone of the upper arm (brachium) in the Vertebrates. 

 HY'A-LINE (Gr. hualos, crystal). Crystalline or glassy. 

 HYD'-A-TIDS (Gr. hudatis, a vesicle). The vesicle containing the larval forms 



(Echinococci} of the tapeworm of the dog. 



HY'DRA-FORM. Kesembhng the common fresh-water polype {Hydra} in form. 

 HY'DRA. 

 HY-DRO-CATT'LTJS (Gr. hudra, a water-serpent ; and kaulos, a stem). The main 



stem of the coenosarc of a Hydrozopn. 

 HY'-DRO-CYSTS (Gr. hudra ; and kustis, a cyst). Curious processes attached to 



the coenosarc of the Physophoridce, and termed " feelers " (Fuhler and Taster 



of the Germans). 

 HY-DRCE'CI-UM (Gr. hudra ; and oikos, a house). The chamber into which the 



coenosarc in many of the Calycophoridce can be retracted. 

 HY-DROI'DA (Gr. hudra ; and eidos, form). The sub-class of the Hydrozoa, 



which comprises the animals most nearly allied to the Hydra. 

 HY-DRO-PHYL'LI-A (Gr. hudra; and phullon, a leaf). Overlapping append- 

 ages or plates which protect the polypites in some of the oceanic Hydrozoa 



(Calycophoridce and Physophoridce). They are often termed " bracts," and 



are the Deckstucke of the Germans. 

 HY-DRO-RHI'ZA (Gr. hudra; and rhiza, root). The adherent base or proximal 



extremity of any Hydrozoon. 

 HY-DRO-SO'MA (Gr. hudra; and soma, body). The entire organism of any 



HydrozoiJn. 

 HY-DRO-THE'CA (Gr. Jiudra f and theke, a case). The little chitinous cups in 



which the polypites ot the Sertularida and Campanularida are pro- 

 tected. 

 HY-DRO-ZO'A (Gr. hudra ; and zoon, animal). The class of the Cwlenterata, 



which comprises animals constructed after the type of the Hydra. 

 HY-MEN-OP'TER-A (Gr. humen, a membrane ; pteron, a wing). An order of 



Insects (comprising Bees, Ants, etc.) characterized by the possession of four 



membranous wings. 



HY'OID (Gr. Y / eidos, form). The bone which supports the tongue in Ver- 

 tebrates, and derives its name from its resemblance in man to the Greek 



letter Y. 

 HY'PO-STOME (Gr. hupo, under ; stoma, mouth). The upper lip, or " labrum," 



of certain Crustacea (e. g., Trilobites). 



HY-RA-COID'E-A (Gr. hurax, a shrew; eidos, form). An order of the Mam- 

 malia constituted for the reception of the single genus Hyrax. 



IOH-THY-O-DOR'Y-LITB (Gr. ichthus, fish; doru, spear; lithos, stone). The 

 fossil fin-spines of Fishes. 



