100 GLOSSARY. 



Lythoctsts. Gr. lythos, stone, kystis, a bladder. Sense organs in hydroids, 



consisting of transparent capsules inclosing round transparent concretions. 

 Manubrium. Lat. a handle. The central polypite suspended from the interior 



of the umbrella of hydroids. 

 Mesoderm. Gr. mesos, intermediate ; derma, skin. The middle layer of 



sponges, &c. 

 Mesothobax. Gr. mesos and thorax. The middle division of the thorax in 



insects, carrying the second pair of legs. 

 Peristome. Qr.peri, about ; stoma, a mouth. The area surrounding the mouth 



in sea-anemones. 

 Pneumatocyst. Gr. pneuma, air ; kystis a bladder. The air-sac contained in 



the pneumatophore, see below. 

 Pneumatophore. Gr. pneuma ; phero, to carry. The float of certain hydrozoa 



(PhysophoridcB.') 

 Polypite. Gr. polus, many ; pons, foot. The separate animal or zooid of a 



hydrozoon. See Hydranth. 

 Protoplasm. Gr. protos, first ; plasso, I mould. The jelly-like matter which 



forms the basis of all tissues. It is identical with the sarcocle or flesh of 



protozoa. 

 Sac. Lat. saccus, a bag, a small cell. 

 Sarcode. Gr. sarx, flesh ; eidos, form. The protoplasm of protozoa, &c, 



which see. 

 Spadix. Lat. spadix, a broken palm branch. In zoology a hollow process 



occupying the axis of the generative buds of hydrozoa. 

 Spoeosac. Gr. spora, a seed, and sac. The body containing the ova of hydrozoa. 

 Somatic Fluid. Gr. soma, the body. The fluid which contains digested food, 



and taking the place of blood, circulates through the body of hydrozoa. 

 Tentacles. Lat. tentaculus, a little arm. The arms or prehensile organs of Sea- 

 anemones, &c. 

 Thread Cells. Cells containing an extensible microscopic thread, possessing 



stinging properties, common among the Cwlenterata. 

 Thorax. Gr. a breastplate. The chest. 



