Among the tailed batrachians, which include the animals popularly called *lizards* and more correctly, newts and salamanders, the aquatic species lay their eggs in water. They are de posited one in a place, or in small dusters, and generally attached to water-weeds or bits of wood or stone on the bottom of the pool. The land varieties lay their eggs in a damp hole in the ground or in a hole in a tree trunk, some times as high up as 30 feet abOve the ground. The eggs are spherical for all species and gen erally about one-fourth of an inch in diameter. The giant anuatic salamander of Japan and China lays up to 500 eggs, which are in several separate clusters, the members of each being connected together by a membranous *string.* This same peculianty has been noted in the case of a small water salamander common in the streams of the eastern United States. There are, however, quite a number of species of these animals which do not lay eggs but bring forth their young alive.
Eggs of Fishes.— Most species of fish are oviparous, some are viviparous and a few ovo viviparous. Owing to the obvious difficulty of observing animals whose habitat is deep water, there are many species about which nothing is known concerning their modes of reproduction.
Most of the shark-like fishes are viviparous, but in those cases in which they do lay eggs the latter are of considerable size, and, as with the common ground dog-fish, they are provided with a °shell° of tough, horny structure. Within this is found a yolk surrounded with an albuminous layer, so that there is a close resem blance tp the eggs of birds. The shell of the dog-fish egg is quite a well-known seashore object, with its oblong cushion shape and the long spinous hooks at each corner. It is only in fishes of this class that an envelope worthy of the term °shell° is produced. The eggs of other fishes have only a thin membranous cov ering, although in some cases this is hard to a degree and often adhesive, fixing itself to the first solid object that it comes in contact with. A few species lay their eggs on rocks or in clumps of weeds between high and low water, so that they are exposed to the atmosphere twice a day by the fluctuating tides. Others, among which are some of our common cat fishes, lay but a few eggs and carry them around in the mouth until they are batched. Reference has already been made to the great fecundity of the cod and turbot. In the same classification belong the salmon, shad and her ring and many others who come up from deep water to lay their eggs in a wholly unprotected condition in the shallow shore or inland waters.
The eggs of the herring, like those of the perch, are adhesive, and in this respect have a certain advantage against destruction. Most of the deep-sea fishes, however, lay egg-masses which are buoyant and float about on the surface sub ject not only to the appetites of other dwellers in the sea but also to those of sea birds, so that comparatively few eventually reach maturity.
The eggs of several kinds of food fishes are esteemed as food delicacies, notably the roe of shad and herring, and caviar (qv.) made from the eggs of sturgeon and other fish.
Eggs of Insects.— When it is recalled that there are upwards of 300,000 known species of insects it will readily be seen that no befitting mention of the well-nigh innumerable varia tions in egg production and egg forms can be attempted within the necessary limits of this section. The student must be referred to the appropriate volumes noted in the bibliography below.
Most insects are oviparous, but within a few species the eggs are hatched within the body of the mother. The number of eggs laid as a °brood° ranges from one or two up to thou sands. As a rule the number laid by the com moner insects is from 100 to 300. They are laid generally in groups of detached eggs or in small masses, though often singly, and attached to a leaf or twig of the plant which will fur nish suitable food to the newly-hatched larva. The habits of bees and wasps in this respect are well known, and it needs only this passing mention to bring to mind the combs of wax or paper or the mud cells in which these insects lay their eggs and raise their young. The cluster of eggs rolled up in silk by the common house and garden spiders is a familiar sight.
Undoubtedly the eggs of the butterflies and moths are the most interesting of all among the insects. They are very small, and within the outer membranous coating they contain the egg-cell and a supply of liquid food for its de velopment. In form there is the greatest possi ble variety — globular, thimble-shaped, pear shaped, cylindrical, purse-like, lens-shaped, turban-shaped and a multitude of other forms for which no simile can be found. Under the microscope they exhibit a wonderful variety of flutings, sculpturings, lacework and other forms of decorative surfaces. Although most of them are white or greenish their colors range into cream, yellow, red, blue and brown. Generally but one laying is made, but there are a few species which produce two or even three broods in the season. In tropical countries there may be several more than this during the longer life of the adult females.