surface of the water.) Great clusters of hair-like strings of eggs in linear at' 

 rangement are apt to be midge egg-masses. Balls of jelly about the size of 

 marbles and containing many minute eggs are likely to be the egg-masses of 

 caddis flies. Occasionally in autumn great numbers of tiny objects resembling 

 fig seeds may be found along the margins of lakes and ponds. These are not 

 eggs but may be the gemmules of sponges or the statoblasts or reproductive 

 units of Bryozoa. A sponge gemmule may be recognized by the tiny spines 

 or spicules embedded in the outer wall. The statoblasts of the common Bryozoa 

 are either smoothly margined or else bear a ring or rings of tiny hooks designed 

 to anchor them in some safe harbor for the winter. 



Eggs found on land may be identified by texture, color, size, shape and 

 other characters. Gelatinous eggs, either singly or in bunches, are usually 

 those of moUusks or amphibians. Eggs with tough outer coverings may be 

 those of moUusks, arthropods, reptiles or birds, the invertebrate eggs usually 

 being smaller than those of vertebrates. More detailed discussions of the eggs 

 of the different groups follow. 



Most terrestrial mollusks (snails and slugs) deposit separate eggs which 

 may cling together in bunches. The eggs vary from spherical to elliptical 

 shapes and may be hard-shelled or gelatinous. Many land mollusks deposit 

 soft, milky eggs under boards or logs or on vegetation. Helix and related genera 

 as well as some of the other land snails lay clusters of shelled eggs. One large 

 tropical species lays oval, shelled eggs much like those of reptiles. 



Arthropod, especially insect, eggs are so varied and numerous as to dis- 

 courage description. A few generalities may be pertinent, however. Most 

 of the eggs of this group are very small, shelled, and vary somewhat from 

 simple oval or spherical shapes. Many are cylindrical or spindle-shaped, some 

 have elaborate markings or flutings, and some open by tiny caps or lids. They 

 may be found singly or in groups and may be white or colored. Structures 

 often mistaken for eggs are the woven cocoons and the ornamented chrysalides 

 or pupa cases of moths, butterflies and other insects. The common "ants' eggs" 

 often purchased with the mistaken idea that they make good food for pet baby 

 turtles are not eggs but ant pupae in their cases. Some arthropods, such as 

 spiders, deposit groups of eggs within fibrous cases. 



Most of the amphibians that lay their eggs on land are salamanders of the 

 family Plethodontidae. They deposit unpigmented eggs either singly or in 

 bunches in damp places under logs, stones or moss. In most species the female 

 can be found with or near the eggs. One of the Ambystomidae, Ambystoma 

 opacum, deposits bunches of pigmented eggs during the autumn under vegeta- 

 tion on the dry or semi-dry floors of temporary ponds. 



Reptile eggs are either spherical or ovoid and vary from about the size of 

 peas up to the size of golf balls or larger. They are usually white and have 

 tough, leathery shells which can be torn but which do not readily crack. It is 



540 



