EGGS or REPTILES AND AMPHIBIANS. Most reptiles are oviparous, laying eggs. either globu lar or oblong in shape, closely resembling birds' eggs in composition of yolk, albumen, and cov erings, except that the shell is not calcareous, but of a tough, yellowish-white, parchment-like (co•i aceous) material. "These are usually deposited in holes and left to hatch by the heat of the sun. In the [case of] the crocodiles they are deposited in a rough nest, and guarded by the mother. In all cases development has only pro gressed to a very early stage when the deposition of the eggs takes place. and it is only after a more or less prolonged period of incubation that the young, fully formed in every respect. emerge from the shell and shift for themselves." These eggs are most numerous in the case of the tur tles, numbering from 25 to 250, and are buried in the sand of sea-beaches and river-banks. Those of the fresh-water species are mostly nauseous. lint the eggs of sea-turtles are excellent food, will keep fresh a long time, and are extensively gathered. the people of many tropical countries subsisting largely upon them in their season. They are also much fed upon by wild animals. lizards and serpents do not lay eggs, but are viviparous; but the pythons not only lay them, hut incubate them within the circle of their coiled bodies.
TI1E EGGs or TIIE AMPHIBIANS. These differ from eggs of reptiles in being small, numerous, having comparatively little food-yolk, and are usually laid in the water inclosed in gelatinous masses or ponds. Sometimes they float or lie upon the bottom, or attaehed to submerged plants, or are laid under logs or stones; and in a few eases they are carried about by one or the other parent until they hatch, or the Mother coils about them in an underground cell. They are
devoured by sonic aquatic. animals.
n.cs FISIIEs. The fishes may be broadly divided into 'cartilaginous' and 'bony.' which essentially in respect to their eggs. The cartilaginous fishes—sharks, rays, etc. (qq.v.)— produce in each case only a few eggs, which are proportionately nearly as large as those of birds or reptiles. and which, like those, are inelosed in envelopes and contain much yolk and sennliouid albumen. Some species are vivipa rous. ill those which extrude their ova in a more air less adVanced stage of development each egg is covered by a dark-I rown ehitinons ease. which most commonly is flat and four-cornered. with tuW isted filamentous appendages at the corners, by means of which it becomes attached to sea weeds and the like. These are the 'sea-purses' of fishermen.
The bony fishes mostly emit minute eggs, usu ally called 'spawn,' in vast quantities, a single sea-iish producing, two or three hundred thousand in some cases. These are cast into the water and contribute a large part of the food-supply of 0(1001 ie nineteen-twentieths, prob ably, being quickly devoured. Some float at or near the surface; others sink to the bottom. Some fresh-water fishes. however, deposit their eggs in Iiretetred nests, where they are guarded and attended until they hatch. (See NIDIFICA TION.) This reduces the proportion of loss so greatly that comparatively few need be produced. and they are far larger, relatively, than in the other ease. The eggs of such fishes as the shad, under the name of 'roe.' and of the sturgeon (caviar). enter largely into the list of human comestibles.